When Suleiman I began the first siege of Vienna in 1529, he sent a letter to the defenders saying that he'd have his breakfast within the city walls in three days. Two weeks later, the Viennese sent back another letter telling him that his breakfast was getting cold.
19th Century
While no timetable was ever mentioned, American War Hawks at the beginning of the War of 1812 declared the conquest of Canada to be "a simple matter of marching." With capable commanders in Canada like Isaac Brock and Tecumseh, all US invasion attempts ended in failure, though the Americans did succeed in burning York (now Toronto), the capital of Upper Canada... which led to the British and Canadians burning Washington, D.C. in response.
At the start of The American Civil War, both sides assumed it would end in a quick victory. Confederate Secretary of War Leroy Pope Walker even predicted he would be able to mop up all the blood spilled with a handkerchief. The fact that Fort Sumter surrendered without any casualties from the shelling contributed to this ideanote The first casualties of the war from each side happened at Fort Sumter during the surrender ceremony. Six Union soldiers wounded by a spark setting off a pile of cartridges, and a Confederate who accidentally poisoned himself by drinking some confiscated alcohol, not realizing that it was rubbing alcohol meant for cleaning surgical implements rather than liquor. The Confederate lived after getting his stomach pumped, two of the Union men did not.. Instead, the war lasted four years and killed more Americans than any war before or since.
20th Century
In 1903, on the eve of the Russo-Japanese War, V.K. Plehve, Russian Minister of the Interior, said: 'What this country needs is a short, victorious war to stem the tide of revolution.' The war was neither short nor victorious for the Russians, and the first Russian Revolution came in 1905, immediately after the war, partly because of the war itself. Though the uprising was contained, discontent continued to fester until World War I came less than a decade later, bringing down the House of Romanov with it.
World War I
Almost every major belligerent at the outset of World War I had some kind of plan that they thought would win the war in a short time, such as the so-called Schlieffen Plan of the Germans to capture Paris and knock France out of the war before turning to take on Russia, or Great Britain's scheme to make the German economy implode using their ability to manipulate international trade and financial markets. The general prediction was that the war would be bloody, decisive, and short. (They got two out of three predictions right.) Indeed, they figured there was no way that a full-blown modern war between the great powers could last very long, because pretty soon one side or the other would burn through its manpower, ruin its economy, and incite revolution against the government from the sheer strain of keeping it up. Thus, they planned for a campaign lasting months rather than years. For example, they conscripted large numbers of factory workers away from the home front and didn't bother manufacturing large stockpiles of ammunition, thinking they needed to call up all their manpower at once for one do-or-die campaign, and that the fight would be over one way or the other before any investment in war production had a chance to bear fruit. Even the Ottoman leaders—who were the rare pessimists in recognizing that they weren't prepared for it—shared the assumption that the war would be short, which was the main reason they let themselves get pressured into joining by the Germans. Basically their plan was to find excuses to drag their feet and let Germany do most of the work, so that hopefully the war would be over before they needed to do much of anything.
As it happened, nobody’s plans succeeded as they hoped. On the Western front, the Germans made gains into France but were stopped from taking Paris in the Battle of the Marne; at this point the Germans started digging trenches to secure the line against the French and British, who did likewise after they failed to dislodge the Germans. Both sides raced toward the sea in unsuccessful attempts to outflank each other, resulting in an unbroken line of trenches stretching all the way from the Swiss border to the French coast. These early trenches were built in a hurry and could have been broken through with a well-executed attack, but the problem was that everyone had already run out of manpower, ammunition, etc. due to the lack of preparation for a longer war, meaning that by the time they had rebuilt the capability for an offensive, the trench defenses had been upgraded to such a level where it was almost impossible to break through. Theaters other than the Western Front involved more maneuver warfare and territory changing hands, but the net result of those was still an attritional struggle rather than decisive victory for one side or the other. The war would drag on for four years before an eventual Entente victory over the Central Powers. The funny things is that the complete demographic, economic, and government collapse described in the pre-war predictions is what finally brought down the main Central Power of Germany, but the prognosticators had disastrously underestimated how long it would take for this to happen. Incidentally, this also was achieved by Germany against Russia, which pulled out of the war following the Bolshevik Revolution.
In February 1915, Entente forces started the Gallipoli campaign in an attempt to break the stalemate by knocking out the Ottoman Empire, who were allied with Germany and Austria-Hungary. The Entente hoped that by securing the Gallipoli peninsula and Dardanelles strait, British ships could sail to the capitol Constantinople where they would subsequently bombard the Ottomans into submission. What was supposed to last no more than a month turned into 8 months of the same brutal trench warfare seen on the Western Front. The invasion failed spectacularly as not only did the Entente fail to plan accordingly with no air superiority and specialized landing craft, but they badly underestimated the Ottoman Empire, which was originally written off as the "sick man of Europe". While in part this reputation had been well-earned (inefficiency and corruption were rampant in the Ottoman government), racist assumptions of European superiority over Turks made the Entente expect this to extend to the fighting abilities of the Ottoman soldiers.
Italy is a rather special case, in that they could have actually ended the war by Christmas twice had it not been for unexpected turns of events: being a member of the Triple Alliance before the war everyone expected them to join on Germany and Austria-Hungary's side and attack France, only to pull the rug from under everyone when the Italian government declared neutrality (as the Triple Alliance was a defensive pact and Austria-Hungary declared war first, they claimed they weren't obliged to enter the war), thus allowing France to concentrate all forces in the north and successfully defend Paris; a year later they entered the war and the government expected a quick victory but commander in chief Cadorna, knowing the appalling state of the Italian army's equipment, ordered instead a token offensive before digging trenches at a moment the entirety of the Austro-Hungarian army was on the Russian front and Vienna itself was vulnerable, and by the time this was discovered much of Austria-Hungary's military had been hastily and successfully redeployed.
World War II
During the Second Sino-Japanese War, the Japanese predicted that Shanghai would fall in three days. However, they were not prepared for the strength of their opposition, including a million of Chiang Kai-Shek's elite soldiers trained by German advisors. It took three long and hellish months involving fierce urban warfare before Shanghai finally fell. Then there was the entire war itself; the Japanese were confident that they could take all of China in three months, or at least force a surrender in that time. Instead, China held on for 8 years, tying down half of the Japanese Army until Japan's surrender following the atomic bombings of Hiroshima and Nagasaki and the prospect of a Soviet invasion of the home islands.
At the beginning of the Winter War, Joseph Stalin was expecting Finland to surrender in a couple of weeks - after all, it was a small backwoods country up against a world power - but the war went on for three and a half months and ended in a Pyrrhic Victory for the Soviets: they did force the Finns to concede their border territories, but at a huge cost in both lives and international prestige; the Red Army griped, "We won just enough territory to bury our dead." In addition, this "victory" was the key reason Finland allied with Germany in World War II as Winston Churchill and Franklin D. Roosevelt had refused to tell Stalin on behalf of the Finns to give up his ambition in the country, considering him too vital an ally (the Finns even call it the "Continuation War").
On the morning of June 22, 1941 when the German invasion of the Soviet Union began, Adolf Hitler said to his colleagues, "Before three months have passed, we shall witness a collapse of Russia, the like of which has never been seen in history". To say that Hitler was wrong doesn't even come close to putting it.
Hitler and his generals were overconfident because France had previously been considered a more formidable opponent than Russia, going back to World War I in which Germany managed to knock Russia out of the fight, only to lose to France. This time, in stark contrast, they had completely outmaneuvered and overrun France in just six weeks, expelling the British Expeditionary Force in the process. If the Germans had just curb-stomped the enemy that had beaten them in the previous war, then surely they could knock out the country they'd defeated once already, right? The Soviet Union was still viewed by many experts around the world as a backward country lagging in economic and technological development. The Germans were further emboldened by the fact that the Soviet military had been weakened by Stalin's purges, and the Red Army had just performed rather incompetently in Poland and Finland. On top of all this, the Nazis were convinced that the Slavs were an inferior race of "Untermenschen" who could never match the German people's talent or force of will in battle, and that the "Judeo-Bolshevist" Soviet state was a degenerate, rotting structure which would collapse if they just kicked in the front door.
Having said that, the Germans were still afraid (just as they had been about Russia before World War I) that the Soviet Union with its superior population and resources might grow unstoppable if it were given a few more years to build up, meaning that they had to take it on now while it was still vulnerable. Meanwhile, Hitler saw capturing the farmland of the Ukraine and the oil fields of the Caucasus as the only hope for making his resource-devouring empire self-sustaining, and of giving Greater Germany the necessary resource base for what he saw as inevitable future wars against America and the other 'sub-human' races. The Germans put together the largest invasion force the world had ever seen to accomplish this task, including 3.8 million military personnel, over 6,000 tanks and other AFVs, at least 2,770 aircraft, at least 7,200 artillery pieces, 600,000 other vehicles, and 600,000 horses. The summer of 1941 was the last real opportunity if they were going to do it, since if they waited any longer they would no longer have the fuel reserves to support such a massive invasion. Their entire chance of victory depended on fighting as short a campaign as possible: they didn't have sufficient industrial power or population to win a war of attrition; they didn't want to still be fighting by the time the October rains or winter's cold set in; and since they had to conscript so many of their factory workers to participate in the invasion, the continued functioning of their war industry depended on them being able to defeat the Soviets and send the workers back home to the factories by the end of September. What the Germans were counting on to happen was that their three Army Groups (with the help of divisions sent by their various allies) would advance through the Soviet Union along a 2,900-kilometer-wide front, supporting each other on the flanks when necessary. They would destroy the greater part of the Red Army near the border in massive battles of encirclement, and by the time they captured Smolensk (702 km from their start point, and about two-thirds of their way to Moscow), they expected the Red Army and Stalin's regime to have totally collapsed, leaving them to march the rest of the way to Moscow virtually unopposed; they assumed that partisan activity and attacks on their lines of supply would be minimal. As they advanced they would capture the railways and use them to transport troops and supplies. They would occupy the Western Soviet Union, establishing a defensive line between Arkhangelsk and Astrakhan, and demobilize most of the invasion force.
Now, Operation Barbarossa and the whole concept behind it was fatally flawed because firstly, it was a plan whose timetable might have just barely worked if everything went according to the most perfect, best-case scenario, meaning that it could be crippled if one of any number of possible circumstances happened to set them back; and secondly, the Germans had no plan to fall back on in case this operation failed. Among the obstacles to success, the most obvious was the issue of distance and logistics. The Soviet Union was way bigger than France, and the Germans had never attempted to maintain and supply such a deep push into enemy territory. The farther they got away from the supply dumps at their starting point, the longer it would take for supplies to reach the front line and the more of their own supplies the trucks would have to consume to get there. Given the sheer distance, as well as rather primitive roads, the breakdown rate of both tanks and trucks was going to be ungodly. Railways offered a partial solution, but the Soviets used bigger trains and their rail gauge was wider than in Germany. The Germans intended for troops to advance along the rail lines to capture as much Soviet track and rolling stock intact as they could, and in order to use German locomotives, they'd have engineers reset the gauge as they advanced. If they failed to prevent the Soviets from destroying them first, the Germans would be in the unenviable situation of attempting a major construction project in the middle of an attempted Blitzkrieg. Operationally speaking, the panzer divisions were the mobile spearheads that would lead the charge, but eighty percent or more of the German army was not mechanized. The infantry divisions consisted of men on foot, accompanied by wagons and artillery drawn by horses, moving at essentially the same speed as Napoleon's army in 1812. The infantry would have to keep up a brutal pace, and the panzer divisions would have to periodically stop to wait for the infantry and additional supplies to catch up. Food supplies would be maximized by taking it from the population, and deliberately letting both civilians and POWs starve. Not only was this a crime against humanity, but because the people in many of these occupied regions could barely grow enough food for themselves, it wouldn't go a long way towards supporting the German army. Finally, German intelligence before the invasion was terrible and they didn't have an accurate idea of the full scale of what they were up against. They got the size of the Soviet forces on the border more or less correct but remained in the dark about the millions of trained reservists who were available to replace losses, whereas Germany had practically no reserves or replacements. They were also ignorant of dangerous new Soviet weapons systems such as the T-34 tank.note The T-34 of 1941 actually had a lot of teething troubles which would severely reduce its effectiveness during Barbarossa, and they were not yet available in massive numbers, but German troops had no idea what it was and only noticed the strengths at first, not the weaknesses. Thus, it had an outsized detrimental effect on German morale. When Field Marshal von Reichenau examined a destroyed T-34, he remarked "If the Russians ever put this on an assembly line, we will have lost the war." Overall, the Germans were running the risk that a combination of worse-than-anticipated Soviet resistance and their own logistical hardships would cause the invasion to sputter to a halt before they dealt the knock-out blow to the USSR, leaving them occupying enemy territory, but stuck with a protracted war that they didn't have the resources to handle. It's as if the people in charge were either arrogant enough to think they didn't need a fallback plan because success was guaranteed, or else they didn't bother coming up with one because they recognized how screwed they would be if Barbarossa didn't work.
The invasion seemed like an overwhelming success at first. At that time the Red Army was in the middle of doing a complete overhaul of its equipment, training, and doctrine which aimed to turn it into an effective modern fighting force, a process which was fraught with a lot of confusion and teething troubles. Stalin was aware of his vulnerability during this transition but convinced himself that he could use his diplomatic skills to preserve the non-aggression pact with Hitler at least through 1941, so that when his intelligence sources tried to warn him an invasion was imminent he refused to hear it. Thus, the Red Army was not prepared to defend the border or counter a German Blitzkrieg. Soviet generals couldn't get up-to-date information about the reality on the ground as the Germans ran rings around their troops, leaving them with little choice but to keep throwing reinforcements into the meat grinder while they tried to figure out what to do. The Germans made huge territorial gains and captured hundreds of thousands of Soviet troops in giant encirclements, very much as they had hoped; in the ensuing months they captured Minsk, then Smolensk, and besieged Leningrad. By early October, some German newspapers were already declaring victory in the East. The British and American leaders, seeing the way things were going, agreed that the Soviet Union was probably doomed and started making contingency plans for their collapse.
However, Stalin kept a firm grip on power and the Red Army managed to soak up the damage as it stalled for time, drawing on the large reservist population to replace the loss of numerous divisions. The Germans inspired fierce resistance everywhere through their barbaric conduct: the war of annihilation the Germans had intended backfired on them by motivating the Soviet people to fight to the death since they wouldn’t be any better off if they surrendered. Despite seemingly low German losses overall, they were taking heavy casualties among the panzer troops who made up the spearhead, blunting their offensive momentum. Not to mention, they were facing outrageous mechanical attrition among the tanks and trucks, which was exacerbated by the lack of spare parts. The railways weren't working out either, as the Soviets were very efficient at destroying their rail systems as they retreated, and the Germans couldn't rebuild them fast enough. Because of this, the infantry had to keep marching non-stop for hundreds of kilometers, leading to some men collapsing or even dying from exhaustion! The inability of the infantry to keep up with the Panzers also led to holes forming in the German encirclements around the Soviets, allowing groups of them to slip through and threaten the Germans' rear echelons.
In July, the Germans were in the process of capturing Smolensk, while Leningrad in the north and Kiev in the south were still holding out. The German generals had thought that by this point the Red Army would be collapsing and that they would follow up with an easy March to Moscow. Instead, to their surprise and consternation, Soviet forces were still fighting back and forcing the Germans to do everything the hard way. During the battle of Smolensk, Hitler stunned everyone by decreeing that the advance on Moscow would not be allowed to proceed until Leningrad and Kiev had been secured and that the panzer forces of Army Group Center would be diverted to help Army Groups North and South with these objectives. The generals bitterly protested since they were laser-focused on capturing Moscow, but Hitler thought it too dangerous to advance in the center with the Soviets threatening the flanks, leading him to divert the panzers while temporarily halting Army Group center. Generals such as Guderian and Manstein would go on to write memoirs blaming Hitler for squandering their chance for victory, a claim which ought to be treated with a lot of skepticism. The Germans settled for besieging Leningrad instead of trying to capture it so that Army Group North could continue East, and Army Group South eventually succeeded in capturing Kiev.
Operation Typhoon, the effort to advance and capture Moscow, began on September 30th: Army Group Center, now returned to strength with assets from Army groups North and South, began to move again. By this time, the invasion had missed the original deadline for the completion of its objectives. The Germans had also used up their petrol reserves, leaving them with barely enough fuel to move one Army Group at a time. Once they were past Smolensk the overstretched German logistics chain hit its limits, and the continuous drive east was replaced by a stop-start rhythm as the panzer divisions waited for the infantry and additional supplies to catch up. The situation was the opposite for the Soviets, who had an increasingly easy time moving supplies, munitions, and reinforcements as the front line got closer to their factories and transportation hubs. In fact, this whole time the Soviets had been evacuating their factories and workers from western regions by loading them lock, stock, and barrel onto freight cars, and shipping them far behind the lines so that war production would continue despite the loss of those territories. The Germans were further hampered by the rainy season in October, with their wagons and vehicles getting hopelessly stuck in roads that had turned to mud, and it wasn’t until mid-November when the ground froze that wheeled vehicles could get some purchase.
By December, a small number of German units reached the suburbs of Moscow, where they could supposedly see the light reflecting off the roofs of buildings in the Kremlin. But the bulk of forces were not this far forward, and the tantalizing glimpse of victory would turn out to be a mirage: Germany’s soldiers were totally worn out, and in danger of freezing to death as the temperature plummeted because winter clothing couldn’t be transported from Germany to the front; the supply chain for getting food and ammo to the frontline troops had broken down; Moscow had by this time been heavily fortified against the anticipated attack; and the Red Army had finally succeeded in pulling itself together. When the Germans faltered, the Soviets launched a devastating counterattack that came close to destroying the overextended Germans outside of Moscow and inflicted the kind of mass casualties that the Germans had so far managed to avoid. Hell, even if the Germans somehow could have taken Moscow, there's no guarantee that the Soviets wouldn't have just withdrawn further East and kept on fighting. With the failure of Operation Barbarossa to meet its objectives, Germany got bogged down in the kind of attritional war which they had wanted to avoid at all costs, ultimately leading to defeat.
In 1942, the Nazi Propaganda Ministry created a series of posters with the slogan "Stalingrad is conquered!" in anticipation of their victory in the city. In January 1943, they began destroying these posters as it was becoming clear that the Germans would not take the city.
For Japan, their entire war doctrine was centered around fighting a quick war since they were well aware they lacked the resources, population, and industrial capacity to support a war of attrition. This gave rise to the Imperial Japanese Navy's "Kantai Kessen" (Decisive Battle) Doctrine. Taking what they learned from the Battle of Tsushima, the Japanese figured that they could quickly end a war before it could start by swiftly eliminating the enemy's naval capacity in a single battle. This led to them carrying out the attack on Pearl Harbor on December 7, 1941, under the impression that wiping out the US Pacific Fleet in port would force the US to surrender the Pacific to them. And if the US didn't surrender right away, it would take at least six months to rebuild the Pacific Fleet, which Japan could use to fortify their newly captured territory and deter any future attack, thereby forcing the US to come to the negotiating table. However, they made several critical mistakes in their assumptions.
The Japanese intended to destroy the entire US Pacific Fleet at Pearl Harbor. However, what they didn't know until afterwards was that the US Pacific Fleet's most valuable ships, the aircraft carriers, weren't in port during the attack and escaped damage. These carriers played a crucial role in suppressing Japan's expansion attempts and keeping the United States a relevant naval power in the Pacific. Additionally, nobody at the time realized just how much the battleship's role had diminished and how carriers were the true decisive naval weapon (ironically, Pearl Harbor itself went a long way to establishing this shift), so while the Japanese knew that this was a missed opportunity, they had no idea just how powerful the US Navy still was.
While the damage to the US Pacific Fleet was devastating, the Japanese failed to actually attack the port facilities and infrastructure in Pearl Harbor itself, partially because it was believed that the war would be over before said facilities could make much of a difference. But even though most of the battleships were sunk, they were sunk in shallow water right next to the facilities that would be needed to repair them. This would allow the US to repair the damage to the Pacific Fleet much faster than Japan anticipated.
Another factor that somewhat minimized the damage inflicted by the attack was the fact that it was done to ships in port on a Sunday, meaning that a sizeable portion of their crews weren't on the ships or even on-base. Once the ships were repaired, a good number of their original crew were ready and waiting to resume their posts and sail right back out to cause trouble for the Japanese.
The Japanese heavily underestimated the average American's willingness to fight, taking the country's stance on neutrality and non-interference as a sign of weakness. What they didn't expect was Americans universally angered at what they saw as an attack of treachery, especially since due to a communication error, Japan attacked Pearl Harbor before their formal war declaration reached the US. Public support for going to war skyrocketed and since Japan was allied with Germany, that gave President Franklin D. Roosevelt the perfect pretext to get involved in the war in Europe. Congress subsequently declared war on the Axis in a near unanimous vote.
While Japan was well aware of America's industrial superiority, even they couldn't predict the sheer scale of its wartime production. The US not only largely restored the US Pacific Fleet to its original condition, but massively expanded it with hundreds of new ships of all types by the time the war ended. Between 1943 and 1944 alone, the US Navy commissioned more ships than the IJN had in the seventy years of its existence.
Japan's massive success at Pearl Harbor also ultimately backfired, because with the US losing all of its battleships, that forced the USN leadership to massively revise their Pacific strategy to instead use their lighter ships and aircraft carriers to conduct hit and run attacks on the Japanese and avoiding committing to a head on battle. This inadvertently thwarted Japan's Kantai Kessen Doctrine, and they had to resort to attacking the island of Midway to draw the cautious American carriers out, a risky gamble that they spectacularly lost.
The end result is that a war that Japan expected to win in six months dragged on for three more years in brutal attrition warfare that Japan had no hope of winning.
Inverted with the Normandy campaign. The Allies predicted that the liberation of France would be a long, drawn-out campaign of attrition. However, once they broke out, the Germans began to rapidly retreat and Paris was liberated within two months. This unfortunately led to major supply problems, as the Allies found themselves advancing on towns they didn't expect to reach until the following spring and the lack of deep-water ports meant supplies had to be driven all the way from Normandy.
On the part of the Allies, the ill-fated Operation Market Garden that took place in mid-to-late 1944 turned out to be their folly in this trope. The plan itself was audacious, comprising of two phases:
Market, where three allied paratroop divisions would seize nine bridges to open a corridor that led straight to the German Border. The planned corridor was along Holland's A50 motorway at the terminus of which rested the Ruhr Valley in Germany, the industrial heart of the Third Reich. The airborne drop to kick off Market became known as the largest airborne operation in history, with more than 34,000 troops, utilizing both paratroopers dropped from planes and towed gliders to bring in heavy equipment. As part of the operation, the involved airborne divisions were reorganized and consolidated into the "First Allied Airborne Army", consisting of the American IX Troop Carrier Command and XVIII Airborne Corps (the latter of which controlled the 17th Airborne Division, 82nd Airborne Division, and the now-famous 101st Airborne "Screaming Eagles" Division), the entirety of British airborne forces including the 1st and 6th Airborne Divisions, the Polish 1st Parachute Brigade, and several other independent airborne units; of the six divisions consolidated, four were utilized in the operation proper. Once on the ground, the regiments would move to their assigned areas and take the key bridges, hopefully with little resistance due to the assumption that German forces in this area would consist of tired, battered conscripts whose hearts were no longer in the fight after four long years, but... well, see below to see how that turned out.
Garden, where, at least according to Monty, the real action would start: British XXX Armored Corps, using the seized bridges and A50 motorway as their ingress corridor, that would ride that corridor straight across the Rhine and punch into Germany to seize the Ruhr Valley, the loss of which would permanently and decisively cripple the Nazi war effort and destroy the last major obstacle between the Western Allies and Berlin itself. The ultimate goal of the operation was to establish the northern half of a massive "pincer" movement which would circumvent the heavily-defended German Siegfried Line; after which, another operation would see to the establishment of the pincer's southern half, surrounding the Siegfried Line and the Ruhr itself. Then, it would be a "simple" matter of "closing" the pincer and forcing the capitulation of the encircled German defenders, in a move that would hopefully spare the Allies from trying to push through the Siegfried Line itself as American General George S. Patton had wanted to do; Patton's plan, while less risky and more guaranteed to work due to sheer attrition, would surely cost more time and lives than Market Garden. It was also hoped that the German forces who, again, were assumed to be little more than weary, war-beaten troops who had barely if any mechanized support, would be too tied up with the paratroop regiments to effectively cut off the A50 before the XXX could make their drive, and, once surrounded, would either surrender immediately or focus more on trying to escape the pincer than to defend the Ruhr.
According to Allied command, if the operation succeeded, it was indeed thought that the War would be over by Christmas, something that, to Eisenhower, made it worth the risk since civilian leaders were already feeling the strain of the war and wanted him to end it as quickly and with as little loss of life as possible. Unfortunately, the plan fell apart almost right from the beginning. German forces, already expecting a push, wired several of the bridges to blow at the first sign that they could be captured; several times, paratroopers got within touching distance of their objectives only to watch as the bridges literally just exploded in front of them for seemingly no reason. Several regiments, most notably the British 1st Airborne, were caught by surprisingly heavy anti-aircraft defenses over their assigned city of Arnhem, resulting in missed or off-the-mark drops, scattering them and causing delays as they attempted to re-organize and retrieve their much-needed supplies, the drop zones of which had been overrun by the Germans. On top of this, instead of the expected non-mechanized conscripts, the paratroopers instead found themselves facing elite German Panzer Divisions, something that the Dutch Resistance tried to warn the Allied forces about, only to be ignored completely. For the XXX Corps, the A50 motorway turned out to have a glaring flaw: something that cut so deep into enemy territory in such a straight line meant it was incredibly easy for the enemy to set up artillery strikes and guerrilla-style raids against, and the A50 soon earned itself the ignominious name of "Hell's Highway". Even with Allied air support running airstrike missions almost constantly, the XXX's advance bogged down to a crawl. In Arnhem, the supplies-starved 1st Airborne managed to organize but were forced into brutal house-to-house fighting against hardened SS soldiers and armored units. Desperately, they clung to their positions at the bridgehead in Arnhem, their only hope being that the XXX, now heavily delayed, would arrive from across the river to relieve them and drive the Germans back. However, the XXX's momentum finally ran out as the operation ground to a halt in Nijmegen, facing stiff resistance from German anti-tank guns and armored units. For a week the Allies fought on doggedly from both sides but eventually, declaring Market Garden a failure, the Allied forces in Nijmegen fell back from the bridge and re-drew their frontlines there. Eight thousand souls would be left behind in Arnhem; barely 2,200 were able to be rescued across the river while the others were killed or captured by the German forces. World War II in Europe would continue to ravage the continent for another six months.
Over in the Pacific Theater was the Battle of Peleliu. Peleliu Island, located in the Palau Island chain 500 Miles east of the Philippines, was targeted for capture because of its airfield, which was intended to be used as a forward aerial operating base for Douglas MacArthur's upcoming campaign in the Philippines. When the operation began on September 15, 1944, many American commanders believed that, judging by the island’s small size and the seemingly-small Japanese garrison, it would only take the 1st Marine Division three days to secure the island, and this notion was supported by aerial reconnaissance and the Japanese tactics used in the Marshall & Mariana Islands. However, the battle that ensues would last for over two months, with the island not being declared secure until November 27, and was one of the bloodiest in the entire war. This outcome was the result of several factors:
Unbeknownst to the Americans, the Japanese decided to change their tactics. Previous island battles in the Pacific showed them that their previous strategy of beach defenses to outright prevent assault were ineffective, especially since naval bombardment from the Americans would decimate their forces before they actually landed. As such, they decided to instead try a defense-in-depth strategy.
Leading the Japanese Forces on Peleliu was Colonel Kunio Nakagawa. Seeing how the island had very rough terrain, Nakagawa opted to build a series of interconnected caves, tunnels, underground bunkers, and pillboxes within the island to enact this new strategy. These defenses were largely impervious and safe from any naval bombardment.
The bulk of Nakagawa's forces & defenses would be based around the island's highest point, Umerbrogel Mountain, a collection of hills & coral ridges in roughly the center of Peleliu which overlooked much of the island, including the airfield that was central to the Americans' objectives. The Japanese would thus be able to shell much of the island from these positions. The rest of the island was dotted with secondary defenses that the Japanese soldiers could quickly reinforce from Umerbrogel once the Americans began their assault.
One reason why the Americans underestimated Japanese strength on the island was because their reconnaissance wasn't able to spot these new defenses. Much of the island was forested and the Japanese built many of their defenses under the cover of night, as such aerial reconnaissance couldn't properly decipher the full extent of Japanese forces, who numbered in roughly 10,900 soldiers. For added irony, Peleliu was chosen over other Palau Islands because it was believed to be one of the more lightly defended islands in the archipelago.
When the US Marines finally assaulted the island, they found it was far more defended than anticipated, and they suffered heavy casualties. Though the airfield itself was captured with great difficulty after just two days, it was still under Japanese artillery fire from Umerbrogel and thus could not be used to its full extent until the island was fully secure.
Trying to assault Umerbrogel was utterly miserable. The ridge was heavily bombarded by the Americans throughout the operation, making the terrain incredibly rough, full of sharp rocks and broken trees, which made it near-impossible for marines to dig foxholes. Not only that, but the Japanese defenses within Umerbrogel were interconnected, meaning that assaulting one position made the Marines exposed to another, thereby receiving heavy losses.
Ultimately, the 1st Marines were on Peleliu for about a month and took over 6,500 Casualties (including roughly 1,250 killed), thus losing more than a third of their entire division. By mid-October 1944, the Marines were relieved by the US Army's 81st Infantry Division, who took over the island assault. The 81st likewise struggled to assault the Japanese defenses and took heavy casualties (estimated to be 3,100 total casualties, with roughly 400 killed). It wasn't until the end of November that the last Japanese position was finally captured, and the island was declared secured. The entire Japanese garrison of 10,900 troops was wiped out, with only three hundred men taken prisoner. Col. Nakagawa himself committed ritual suicide in the last days of the battle.
In fact, the 1st Marine Division was so decimated from Peleliu that it was put completely out-of-action for over six months after the battle, and would not take part in another major operation until the Battle of Okinawa in April 1945.
In one final insult-to-injury, the Battle of Peleliu took so long that by the time the island was finally secured, it lost its strategic value. On October 17, 1944, while the island battle was still raging, General MacArthur began his long-anticipated campaign in The Philippines. And by the time the battle finally ended, the US was able to establish a solid foothold on the Philippine island of Leyte that largely rendered the airfield on Peleliu moot. It was never used for any future operations for the rest of the war. It is for this reason that the Battle of Peleliu remains one of the most controversial of the Pacific War, with many arguing that the island, along with the thousands of American and Japanese Casualties, could have been avoided entirely and the outcome of the war would not have changed.
The Cold War
Before the 1948 Arab-Israeli War, one Arab general infamously claimed, "This time next week we will be eating lunch in Tel Aviv." Turns out, not so much.
During the Korean War, General Douglas MacArthur was quoted saying this almost word-for-word about the progress of coalition forces, despite Chinese troops having already crossed the border and successfully ambushing UN forces. Because the Chinese troops retreated after running out of logistics. MacArthur assumed the UN forces' massive advantages in firepower and air support would mean that his "Home-by-Christmas Offensive" would easily succeed. Instead, the Chinese army launched a second, even larger offensive that drove the UN out of North Korea and turned the war into a bloody stalemate.
Subverted during the last leg of The Vietnam War. When the final offensive began in December 1974, the North Vietnamese declared that they would win the war by Ho Chi Minh's birthday (May 19). They captured Saigon, ending the war, on April 30, 1975. This was helped by how the South Vietnamese military completely collapsed during the early weeks of the campaign, beyond what the North had expected.
After the Hole in Flag, a bunch of Chechen rebels unilaterally declared independence from Russia, prompting Russia to intervene to restore order. Russia believed that the Chechens would be mopped up quickly. Instead, the war dragged on for nearly two bloody years, and, humiliatingly, Russia had to concede a self-governing status to Chechnya afterwards. When Russia decided that it didn't like the arrangement after all, another war followed, this time lasting over eight years, followed by another eight years of small-scale insurgency before Russia (barely) asserted control. Ultimately, it did little more than showcase that the once-feared Red Army was not even a shadow of its former self.
Inverted during The Gulf War. General Colin Powell famously told the press that the war wasn't going to be a one day affair and "it's not going to be over by the next commercial break." This was colored by the American experience in Vietnam, a very long, costly, and bloody war. However, once US troops went in after a six-week bombing campaign to weaken Iraq, the war actually ended up lasting just four days.
21st Century
The War on Terror
A popular joke in the United States after 9/11 was "What is Osama bin Laden going to be for Halloween? Dead." Bin Laden escaped capture and lived for almost ten more years.
A complaint occasionally fielded about the American public about The War on Terror was that the initial organizers vastly underestimated its length and complexity despite warnings from US military officials that they were in for a very long campaign. Only two months after the invasion of Iraq, President George W. Bush declared that major combat operations had concluded in Iraq with his infamous "Mission Accomplished" speech. The Iraq War would actually continue for another eight years, following his successor Barack Obama into office. The greater War on Terror, begun in 2001, is still ongoing. Much of this is because America believed that Saddam Hussein was an unpopular ruler and all they had to do was take out Iraq's army (which had been written off as garbage since the Gulf War) and Iraq would happily reform into a democracy—unfortunately, while they were right about Iraq's army rolling over like a dead dog, they were only half-right about Saddam's popularity; while his brutal methods and regime meant he was by no means beloved, the one thing he did do right was keep a country as large and diverse as Iraq relatively stable in a region of the world that had been at war with itself for centuries. Once Saddam's regime toppled, so did the stability, as political and ethnic lines quickly began to deepen. With the American military being seen as outsiders at best, and invaders at worst, their mission to bring democracy soon bogged down as insurgents replaced the Iraqi army, bringing with them non-conventional tactics that a modern military force were simply not ready to handle.
In March 2015, Nigeria claimed that it would push out the militant Boko Haram, which had occupied northeastern Nigeria, in a month. The operation lasted for almost a year, while the insurgency continues to this day.
Russo-Ukrainian War
On February 24, 2022, President Vladimir Putin of the Russian Federation announced a "Special Military Operation" in Ukraine, which was immediately followed by the Russian armed forces invading Ukraine simultaneously from the north, south, and east. Russia planned to use its military to quickly depose the pro-European Ukrainian government; install a new pro-Kremlin government in its place; disarm the country and prevent it from joining NATO; ensure the security and "independence" of the Russia-aligned Donetsk and Luhansk separatist states in the Donbas; and tighten its control over recently-annexed Crimea. This "Special Military Operation" (they still refuse to call it "war" to this day) was supposed to be a complete walkover against an inferior opponent, but instead Russia ended up in a grinding war of attrition where it suffered both military embarrassments, major geopolitical setbacks and a massive human capital flight unseen since the Russian Civil War a hundred years earlier.
Despite Putin and his spokespeople not revealing their expected timetable in their public declarations, Ukraine would subsequently claim to have captured secret Russian plans dated January 18th, describing an operation to take over Ukraine that was supposed to last 15 days, from February 20 to March 6. The execution of the Russian invasion supports the idea of a short campaign: it included elite paratroopers dropping behind enemy lines to capture airports, motorized troops racing ahead of their supply lines to capture objectives, and a caravan of armored vehicles bypassing centers of resistance as they attempted to drive straight into the capital city, Kyiv. Russia probably thought their Decapitation Strike would topple the Ukrainian government within three days or so, and that the rest would just be mopping up. They were so certain of their quick victory that they allegedly brought along parade uniforms for a victorious march through Kyiv's main Khreshchatyk Street, with awards for the "special military operation" already pinned to them.
At a glance, the Russian armed forces seemed to have the upper hand. Compared to Ukraine, Russia boasted new and modernized tanks and aircraft as well as plentiful artillery and missiles, while the Ukrainians were dependent on Soviet-era weaponry that has become increasingly scarce even among former Eastern Bloc nations. Furthermore, Russia could easily attack on multiple fronts thanks to its ally Belarus and a network of military bases and rail routes surrounding Ukraine on three sides along with a navy that could assist in assaulting the south. Considering how the Ukrainian army barely existed back in 2014 and had all but rolled over when Russia initially annexed Crimea, the Russians did not take it seriously as a fighting force in spite of its subsequent development and expansion with Western training and material. Putin and his advisers' predictions about Ukrainian resistance were colored by their worldview: to them the Ukrainians and the Russians are essentially one people, and they considered the existence of an independent state of Ukraine to be "unnatural" and "artificial". According to their conspiracy theories, post-Maidan governments were nothing more than a "Nazi" coup orchestrated by Western powers against the wishes of the majority of the Ukrainian people, so when they invaded they expected masses of Ukrainians to desert, surrender, or even collaborate with their Russian "liberators" against the government in Kyiv.note Thanks to decades of propaganda, in Russia, the defining trait of the Nazis is that they invaded in 1941, barely touching on their antisemitic or authoritarian nature. Because of this, "Nazi" has become a shorthand for any outsider who opposes Russia at all, regardless of their actual political leanings. Lastly, the war planners believed that the bickering Europeans and Americans would fail to form a united front against them, whether during or after the invasion. Ukraine would fall before it could receive any military aid from those countries, and since any economic sanctions against Russia wouldn't hit until the conquest was a fait accompli, the Western European countries that imported Russian energy might lose their stomach for economic retaliation.
However, the invasion started to unravel before it even properly began. The US government collected a large amount of intelligence about the details of the probable Russian invasion and made this information public, causing the Russians to delay the invasion by four days out of fear that their chain of command had been compromised. When the invasion did begin in proper, ironically vindicating the American intelligence community after their multiple failures prior to the Iraq War, it wasn't the awe-inspiring success that many expected. The initial Russian missile and air strikes failed to disable key Ukrainian infrastructure such as power plants, cell towers, SAM sites, and fighter locations, squandering the element of surprise and allowing the Ukrainians to put together a real defense. The Russian Air Force was poorly equipped and inexperienced in precision bombing and suppression of enemy air defenses, preventing them from establishing air superiority. Meanwhile, paratroopers and mechanized forces spearheading the assault failed to secure forward bases and key infrastructure needed to springboard further offensives. Russia was caught off-guard by the Ukrainian people's will to fight, especially since President Volodymyr Zelenskyy and much of his government remained in Kyiv instead of fleeing, providing a major morale boost for the country. Even those who had been expected to collaborate turned against Russia.
The main ground invasion became plagued by fierce resistance from Ukrainian regular and irregular forces (who were equipped with state-of-the-art western Anti-Armor portable weapons, the Javelin missile most famously), weak supply lines that resulted in tanks running out of fuel, poor tactics that left formations vulnerable to ambushes (most infamously the 40-mile long supply convoy descending from Belarus got completely bogged down with nonstop strikes by mobile Ukrainian teams, artillery and drones), unsecured communications that let the Ukrainians spy on everything they were doing, and the inability to implement proper combined arms tactics such as close air support or infantry screening for tanks. At the same time, the delayed starting date meant that Russian forces were hampered by bad weather and terrain as heavy clouds stymied the Russian Air Force and the melting snow turned the passable fields of eastern Ukraine into mud that bogged down Russian vehicles and forced them to use roads in the open, further slowing their advance. Most telling, Russian troops were severely demoralized by the poor logistics, lack of early successes, heavy casualties, mistaken expectations to be welcomed as "liberators" and lack of direction (some even claimed they had no idea they were waging a war). Furthermore, Ukraine's success in saving Kyiv convinced the West to unite quickly for enacting sanctions against Russia and arming Ukraine. Subsequently, while both sides took heavy losses, Ukraine was able to replenish its weapons with Western aid. Although Russia was able to partially stabilize its economy, the sanctions prevented the import of replacement equipment like new thermal cameras and sensors, forcing Russia to divert time and resources away from the front lines and towards making their own versions.
After a month of fighting, Russian forces abandoned their original goal of capturing Kyiv as they were too thinly spread throughout Ukraine and had nothing close to the local numerical superiority required to capture such a large city. Russian forces were instead redeployed to Eastern Ukraine to seize the region and subsequently claim a face-saving victory. Intelligence soon suggested that Putin would try to gain a decisive victory by May 9, which commemorates the Soviet triumph over Nazi Germany. However, the Ukrainians quickly stalled the advance in the east, and Putin's speech on May 9 did not include any announcement of military success or mass mobilization. In fact, Russia's eastern offensive devolved into a stalemate with major breakthroughs failing to materialize (most notably at Battle of Siverskyi Donets that resulted in Ukrainians wiping out an entire Russian battalion tactical group of over 400 soldiers). Then in September, the Ukrainians launched their own counteroffensive that retook most of the Kharkiv oblast and Izyum; this attack was especially disastrous for the Russian military as they suffered heavy losses in equipment and manpower while also losing key supply lines for their forces in Eastern and Southern Ukraine. This counteroffensive also began shortly after the occupying forces held a sham referendum for the Donetsk, Kherson, Luhansk and Zaporizhzhia oblasts to join the Russian Federation, an effort by Putin to salvage something from the invasion. In an attempt to replace lost manpower, Putin announced a partial-mobilization effort that included conscription of Russian men, which was met by angry internal protests and civilians fleeing en masse to avoid the draft. These shocking setbacks and questionable decisions resulted in unprecedented internal dissent with pundits, political elites and politicians openly criticizing Russian leadership and some even calling for Putin's resignation.
What was expected to be a quick victory to demonstrate Russian might turned into a quagmire akin to the disastrous 1939-1940 Winter War or the Soviet invasion of Afghanistan. While Russia would've faced some negative consequences even if they had won quickly, at least then they would have only needed to fight the Ukrainians. Instead, the conflict turned into a proxy war with NATO countries giving the Ukrainians as much war material as they want, indirectly killing and destroying Russian power without having to risk their own citizens. The war revitalized NATO instead of scaring/curbing it, with Germany and Poland dramatically increasing their defense spending and formerly-nonaligned Finland and Sweden joining the alliance. Russia's relationship with their non-NATO adversaries also worsened, with Japan ending decades of pacifist "self-defense only" policies to announce their intention to become the third-biggest military spender in the world. As the war dragged on, many of Russia's international allies began distancing themselves from Russia by either refusing to send military aid, publicly condemning the invasion or, in the case of Serbia and Turkey, even aiding the Ukrainians.note Turkish-made Bayraktar drones becoming almost as iconic a part of the Ukrainian arsenal as the American-made Javelin anti-tank missiles. Facing challenges to rearm due to sanctions and isolation, the Russian military has been reduced to buying drones from Iran and artillery shells from North Korea, two nations already isolated from foreign trade due to sanctions. While China and India both continue to do business with Russia, this is widely seen as exploitation rather than support as with sanctions cutting off most other markets, those nations able to buy Russia's oil at well below market price. Europe also managed to make it through winter with little disruption, showing that Russia's claim of the continent being dependent on their oil and natural gas was overstated. Russian foreign arm sales, which were already on thin ice due to 2014 sanctions, collapsed as additional sanctions and battlefield losses resulted in depleted weapon stockpiles and weakened demand for Russian weaponry. And of course, Putin has only strengthened Ukrainian nationalism and hatred for Russia instead of bringing the country back into Russia's sphere of influence. In summary, Russia's larger war goals are permanently lost regardless of what happens on the battlefield from now on, and what was supposedly a brisk march straight to Kyiv devolved into a grim meatgrinder of a conflict reminiscent of that seen in the first half of the 20th century.
Other
In March 2020, just as the COVID-19 outbreak was turning into a global pandemic, some claimed that it would be over within a month and wouldn't be any more dangerous than the seasonal flu, likely believing that it was just a repeat of the 2009 Swine Flu pandemic (which had ended up being no more severe than the ordinary seasonal flu)... it continued to be a pandemic for over three years with over 765 million cases and nearly 7 million deaths before the emergency was declared over by WHO in May 2023.
Likewise, many politicians have prematurely declared the end of the pandemic and lifted safety measures that only resulted in successive waves which proved to be worse than the previous ones. Most infamously, Indian prime minister Narendra Modi ended social distancing restrictions in February 2021, declaring that India defeated the pandemic... a perfect storm of major religious rituals occurring with long breaks in-between having coincided at that time and mass political campaigning for upcoming critical regional elections meant that just 2 months later, the country was experiencing 400,000 new cases per day.
with the slogan "Stalingrad is conquered!" in anticipation of their victory in the city. In January 1943, they began destroying these posters as it was becoming clear that the Germans would not take the city.