Horses were ridden into battle for thousands of years, but most human beings today are unlikely to see one except at a recreational stable. This Useful Notes article exists to talk a little bit about mankind's favorite beast of burden, and how it performs in war.
Horses are not born fighters. Although warhorses have been bred over the centuries for calmness, strength, and stature, a horse's first instinct when facing an individual with a sharp piece of metal and a Slasher Smile is to flee as fast as it can. Fighting is not completely alien to the animal's nature; anything that gets too close to its rear can expect a nasty kick from both hind legs. However, the fact that its main weapon is rear-facing only reinforces the idea that a horse's first instinct when faced with a threat is to flee, fighting only to keep retreating if fleeing fails.
This is somewhat counterproductive to the nature of the animal that rides it; humans are rather more bellicose. (Well, some of them, anyway.) As a result, humans have tried to prepare their mounts for combat in various ways, starting by selecting horses with traits suited to the battlefield for breeding. Horses bred for trust in their rider, size, strength and, above all, a calm demeanor, quickly became the warhorses that carried the richest warriors into battle. Further training was carried out to prepare them to overcome their natural instinct to flee; horses in Roman times were prepared for battle by simulating the noise and clamour of battle so as to make the animal used to such alarming circumstances.
Before horseback riding was widely practiced, elite warriors in ancient China, Greece, India, Egypt, Mesopotamia, and Germanic/Celtic cultures were known to fight from horse-drawn chariots. Chariots usually carried one or two warriors and a chariot driver, and served as highly mobile weapons platforms that could quickly ride into striking distance and then retreat to safety. The Egyptians especially favored chariot archery and used light two-person chariots for lightning hit-and-run attacks, while others such as the Hittites used heavier, slower three-person chariots. A warrior could also use his chariot as a "battle taxi" to drop him off where the other warriors were fighting on foot, while remaining nearby in case he needed to withdraw just as quickly.
However, chariots had a couple of disadvantages compared to fighting from horseback. Chariots were expensive, complicated machines that only elite warriors could own and maintain, and a warrior could not steer the chariot and use his weapons at the same time—hence the need for another person to drive it. Also, while a charioteer could use a spear to thrust at infantry or another chariot, the large wheelbase and rails of the vehicle made employing a short weapon like a sword difficult or impractical. Compared to using a chariot, riding on the horse's back allowed a warrior to guide the animal using his legs as well as the reins, which freed both of his hands to use a bow and arrows or a weapon and shield. In the saddle a horseman could also shift his body enough to avoid a blow or lean into his strike, and could reach out far enough to split a foot soldiers' skull with an axe or sword. The horseback rider began to supplant the chariot around the 9th century BC as Iranian tribes were recorded using bows in battle, and by the 1st century BC the chariot was no longer used in warfare by most civilizations. The invention of the saddle and later stirrups, made it way easier to stay on the horse during maneuvers, so that the cavalryman could fight in melee or on the charge with greater stability.
Once in combat, a man on horseback has several advantages over a man on foot. He is elevated above enemy foot soldiers, which makes him able to rain powerful descending strikes at their heads and upper bodies while his own vital targets are harder to reach. He can get around the battlefield faster than men on foot, meaning he dictates the terms of any fight. For this reason, Archery was initially the favored discipline for those who rode into battle; the samurai didn't call their art "The Way Of Horse And Bow" for nothing. (The sword came later.) This maneuverability was not restricted to ranged fighting however; a common tactic of a cavalry soldier was to canter around an isolated infantryman in a tight circle hacking at him with a weapon while the poor man on the ground had to keep turning and defending. Unless the horseman could be dismounted or the horse injured, the man on foot would inevitably lose as a mixture of fatigue and disorientation took its toll.
Strategically, mounted men could maintain a faster march rate. This allowed them to choose or avoid battle at will. It also made them immensely useful in reconnaissance, scouting, pursuit, and raiding (either with a long-term purpose in mind as with the medieval "chevauchee" on a rival ruler's economy, or simply mounted thieving expeditions with no other purpose which were almost universally familiar among most nomadic societies). Even powers firmly dedicated to infantry tended to keep a few cavalry around for those purposes. For instance, the Anglo-Saxons kept horse-holders in the rear of their lines for a get away if needed and sometimes mounted a small group of men in reserve to hunt down fleeing enemies if they won, but did the main part of their fighting on foot. In sieges, though cavalry declined in importance being incapable of either climbing walls or enduring the stresses of Urban Warfare and cavalrymen often dismounted when taking part in sieges. One of the main uses in a siege was in fact herding the inhabitants of the countryside into the city to put extra strain on the ration supply.
Cavalry comes with certain restrictions and disadvantages, however, which apply both in single combat and in battle. First, cavalry loses much of its effectiveness on rough or hilly terrain; horses do the most damage when they are charging over flat ground. Charging uphill just tires the horses, and charging downhill risks a fatal stumble. Difficult or broken ground can also throw a tightly-packed heavy cavalry charge into chaos just as well as a pike line can be thrown out by the same ground. Besides this, cavalry cannot hold ground or defend an entrenched position the way that infantry can. Men on horseback are like sitting ducks unless they are either moving forward or withdrawing, simply because the horse is a vulnerable target and their combined silhouette makes an easy target for unfriendly archers. A horse is also not as stable a fighting platform as solid ground, and riders could be struck off their horse by other riders' lances or dragged from the saddle by infantrymen with staff weapons. This is why a unit of horsemen did not simply ride up to the enemy and stop to engage them in a stationary slugging match, as you often unrealistically see in strategy videogames. That wastes the advantage of having the mount's mobility, while still exposing you to all the disadvantages it presents. If the infantry did not immediately rout or crumble under a shock attack, in which case the horsemen could ride through them, then the horsemen would have deliver their strike or projectile and veer off to one side, withdrawing in order to minimize the amount of time that they were vulnerable to counterattack.
Whether the rider fell off his horse or had his mount shot out from under him, he was in serious danger. A fall from a horse could cause serious injuries, although it was possible if you were lucky to land relatively unscathed. Contrary to urban myth, no armor worn in battle was so heavy that the rider couldn't rise to his feet after he was unhorsed, and in fact it may have given him some protection from the fall. However, he could quickly be surrounded by hostile infantry just as he was getting to his feet and was likely to be taken prisoner or killed. If the horse happened to fall on its rider, the rider would either be killed outright or become trapped underneath it. Not to mention the fact that horses can become uncontrollable when frightened or wounded and decide to flee the battle, carrying their hapless riders with them!
Horsemen were initially used as fast-moving archers, then evolved into the role of screening the army's flanks. It was eventually Phillip of Macedon's military reforms that really turned the cavalryman into the shocking, battle-winning formations, the picturesque large body of cavalry slamming into disordered infantry and driving them off the field. His son Alexander would go on to win entire battles based around this use of cavalry as the hammer with which to break the enemy army upon an infantry anvil. Cavalry remained relegated to judiciously timed flank assaults and archer support, however, until the coming of the late Roman period, when the Huns proved that heavy cavalry could beat heavy infantry. (This was one of the factors, incidentally, which sealed the still infantry-heavy Roman army's fate... though the Eastern Romans managed to adopt a much more cavalry-heavy army.)
After the collapse of the Western Roman and Hunnic empires, the Normans initially were among the first mounted soldiers who had a decent chance of giving an infantry formation serious pause for thought from the front, breaking the dominance of the infantry soldier through Europe's "Dark Ages", though they preferred to soften such formations up with hails of javelins from horseback and, when that failed, archer support, before punching through the weakened lines with their lances. In the 11th century there was hardly any difference between the cavalry lance and infantry spear except possibly length, and although sources such as the Bayeux tapestry are sometimes ambiguous it seems horsemen used their lances in three ways: overhanded thrusts downward, underhanded thrusts with an extended arm, and charging with the lance firmly "couched" or braced under the arm.
The couched lance took full advantage of the momentum of a man charging on horseback by making sure that the lance would not budge on impact, instead transmitting all the force into the unfortunate target by either penetrating through his armor or knocking him off his horse. By the 12th century the majority of knights were using their lances couched, and the knight's arms and armor underwent a gradual evolution to suit this purpose. From 1100-1300 the lance was about 12 feet in length, and by 1300 it was fitted with a circular hand-guard called a vamplate and a disc-shaped piece called a graper which prevented the lance from slipping under the armpit on impact. From about 1400 a lance-rest was added to the breastplate near the right armpit to help brace the lance against the body, and from the 15th century on the knightly lance was a long, shapely piece of wood with an hourglass-shaped hand grip and a profile that tapered from stout near the hand guard to narrow near the point.
Impact warfare with the couched lance was at its peak from the 12th-13th centuries, with glorious scenes of two knightly hosts crashing together in a charge of lances and then drawing their swords in the furious melee that ensued. The conventional wisdom was that men on horseback were superior to those on foot, and mounted knights symbolically dominated the battlefield, but even during this golden age they were never able to waltz right over ordered and disciplined infantry or to forsake the use of infantry themselves. It was widely recognized, despite contempt for their social status, that infantry were still indispensable in battle. The only time a heavy cavalry assault against infantry really worked was when the enemy infantry lacked discipline or lost formation (usually thanks to already being engaged or, as the Scots found out to their cost, due to archer fire). Once the enemy formation had been broken, the knight was devastating, but that depended at least partially on the enemy, and charges were to a certain extent all-or-nothing propositions. For that reason, wise Medieval generals kept a solid body of disciplined infantry behind so that the cavalry charge, if it failed, had somewhere to fall back to, and the general a reserve force to send in; several battles were won by the infantry after the initial cavalry force had been driven from the field. In terms of formation, heavy cavalry would keep together as closely as possible, giving their horses nowhere to go but forward and the enemy in front nowhere to go but back or towards a relentless press of horseflesh, steel and aggression; trampling was certain either way.
The nomadic horsemen whose fighting style dominated warfare in the steppes of Asia such as the Mongols and the Turkic peoples bred their horses and fought in a distinct manner. In these horse cultures each warrior owned several horses, and their animals were allowed to graze as the tribe moved from pasture to pasture. These horses and ponies were small and bred for hardiness and stamina, compared to European warhorses which were bred more for size and power. An abundance of wide open space and rich grassland was necessary to maintain such huge herds of grazing animals, which fueled a need for territorial warfare. Using lighter armor and equipment than heavy cavalry such as European-style knights, they preferred to use horseback archery for hit-and-run attacks to confuse and weaken their enemies before routing them with a decisive charge. These horse archers used powerful composite bows made of horn and sinew, and while capable of considerable range they also liked to use close-range archery in battle for more penetrating power. However, while arrows could turn the tide of battle, only close combat could finish it. Therefore, both steppe and Muslim armies had significant numbers of heavy cavalry to take on the same shock role occupied by the knight in Europe. The Turks were expert warriors, and the 'Abbasid caliphate in Iraq attracted these steppe nomads to serve as elite troops. This relationship turned out badly when the Caliphate's power went into decline, and the Caliphs had to cede real political power to dynastic emirs, mostly of Seljuk Turkish origin, who only nominally recognizes their authority. It was largely the Seljuk Turks and their horsemanship that the Frankish knights had to contend with during the First Crusade.
The Crusades pitted Eastern and Western horsemanship against each other and demonstrated the advantages and disadvantages of each, although other factors like logistics and morale had as much if not more effect on the outcome of these battles as the type of mounts they rode or the weapons they favored. During the first Crusade, the ill-provisioned Frankish knights lost a huge number of their precious horses due to lack of fodder and water and were harassed through Anatolia by nimble horse archers. In spite of constant attrition and being forced to fight increasingly on foot, the crusaders miraculously managed to win the battle of Antioch against the Seljuk Turks and subsequently capture Jerusalem from the Fatamids in 1099. It wasn't until the 1140s that the Zengid dynasty ruling on behalf of the Seljuk Empire made the recapture of these territories a major priority. In terms of combat effectiveness the Crusaders' full mail armor was reported to reliably stop arrows and lance points, which gave Muslim warriors a hard time in trying to hurt them. Muslim cavalrymen also used mail or lamellar body armor but tended to wear less of it than the Franks, since a fully equipped Frankish knight wore knee-length long-sleeved hauberk, mail leggings, a mail coif, and eventually the great helm. On the disadvantageous side the Franks were were usually outnumbered and full mail armor made heat exhaustion and thirst more of a problem, which presented a logistical challenge when venturing into unfriendly territory. Far from being too dependent on their knights, the Frankish armies could never seem to recruit enough and had to rely mostly on infantry during the existence of the crusader states they founded in the Levant. Recognizing there were also advantages to light cavalry and horse archers, the Franks recruited local mercenaries to pad out their numbers.
In the battle of Hattin in 1187, the combined forces of the crusader states numbered 20,000 against Egyptian Sultan Saladin's army of 30,000 but the odds were even more lopsided in the cavalry department: Saladin had 12,000 cavalry of various types while the Franks had 1,200 knights, 3,000 light cavalry, and 500 Turcopoles (mercenaries who fought as mounted archers). This was a contributing factor in the Franks' disastrous defeat on the horns of Hattin, after which Saladin captured Jerusalem. During the Third Crusade that followed, both Saladin and King Richard the Lionhearted of England proved themselves to be very able generals. The result was that Jerusalem remained under Muslim rule but the other Crusader States were given a new lease on life. It was eventually the Mamluk Sultan Baibars who accomplished most of the rolling back of the Latin footholds that remained. However, even the fall of the last foothold in Acre in 1291 did not the age of crusading, and many fights between Latin Christian Knights and Muslim cavalry such as the 1396 Battle of Nicopolis remained in the future.
The greatest success of steppe nomads in warfare measured by territory conquered was achieved by the Mongol Empire in the 13th Century. Genghis Khan was recognized as the first Great Khan in 1206, having united the Mongol tribes under his rule. Genghis was able to mobilize huge numbers of steppe cavalry and used a combination of pragmatic and ruthless policies to subjugate and rule ever more territory. About six out of every ten horsemen were light horseback archers while the other four were heavily armed and armored lancers. Mongol horsemen could travel up to 70 km in a day on their small horses by regularly changing mounts, outracing their opponents' communication lines to take them by surprise. They also proved surprisingly adaptable by becoming experts at siege warfare. By the time of his death in 1227 his conquests stretched from Mongolia to the Caspian sea, and this was only the beginning as his son and first successor Ogedei Khan expanded the empire even further. Many settled agricultural empires that had been highly powerful were absorbed into the empire, becoming the centers of four major Khanates within the empire: The city of Kiev was sacked in 1240, putting Russia under the Khanate of The Golden Horde; Genghis' Grandson Mongke Khan sacked the Abbasid capital of Baghdad in 1258, leading to the establishment of the Ilkhanate dynasty in Iran; and another of Genghis' grandsons, Kublai Khan, defeated the Song Dynasty in 1279 and established the Yuan dynasty in China. These, along with the Chagatai Khanate in Central Asia, were part of an empire that was spectacular in its day but lacked long-term viability. It was impossible to maintain a decentralized empire purely by military power over such a diverse swath of Eurasia, especially as native political actors gained enough military cohesion to resist them, and the Mongol Khanates eventually fell to the new dynasties that opposed their rule such as the Ming Dynasty, the Mamluk Sultanate, and the Grand Duchy of Moscow.
During the 14th century in Western Europe, it became clear that mounted knights could not afford to be over-confident and that they would have to cooperate with infantry in order to stay relevant. Knights suffered humiliating defeats when they charged infantry directly without any tactical advantage, but they tended to win decisively when they first flanked the enemy or used arrows to break up their formations. In addition, the practice of dismounting from horseback in order to help the infantry hold a defensive position was used by the English against the French during the Hundred Years' War from 1337-1453. Massed English longbow fire was well-suited to taking the momentum out of a French cavalry charge before it crashed into the dismounted English men-at-arms, who did the heavy hand-to-hand fighting: The French charged the English about 16 times during the battle of Crecy in 1346, but were forced to quit the field at the end of the day with appalling losses. The French for their part dismounted to attack the English at Poitiers in 1356 and Agincourt in 1415 so that their horses would not be shot out from under them, but they still lost these battles to the English for a number of reasons including the poor quality of French discipline, the terrain, and the cornered ferocity of the English archers and men-at-arms. It is important to note that the longbow was not a magical weapon that could annihilate hordes of armored knights on its own, and the English defensive battle tactics would have never have worked without choosing the battlefield carefully so that there were obstacles such as forests and marshes preventing French cavalry from attacking them in the flanks or rear. It can be argued—though not proven—that the French could have hypothetically won a few of these battles if the different parts of their army hadn't attacked the English in a disorganized manner. On the whole the French were more successful when they pursued a Fabian strategy of letting the English march outside their cities ineffectively and then recapturing territory once the English army had left. The 15th century saw the beginnings of national as opposed to feudal armies, and France eventually solved its problem of poor discipline from its knights by creating well-regulated companies of ordinance on the state payroll. The use of pikes, halberds, and guns in warfare was increasing, but the nobility still fought as knights and emphasized how the values associated with chivalry (coming from the French word "chevalier", meaning "horseman") granted them their right to lead in battle. Even though they frequently dismounted to fight, the horse was still the visible symbol of their social class and warrior culture.
By the start of the 16th century, full armor for the horse as well as its rider meant that heavy knights or "gendarmes" (French, "gens d'arms") had been made nearly invulnerable, and they stood a good chance of scattering enemy pikemen and gunners if they charged with lances in sufficient numbers. The problem was that full armor for a man and horse carried an exorbitant cost, and it was an uphill battle for any ruler to maintain full-strength units of drilled and equipped super-heavy cavalry. Various sovereigns such as Henry VIII of England, Maximilian I of the Holy Roman Empire, and Francis I of France were building up their states and expanding the size of their armies to compete with each other, but because of its wealth and organizational capacity only the French crown was really able to maintain companies of nobles and gentlemen on armored horses in as large a proportion as they would have liked. There was an explosion of recruitment in German and Swiss mercenary infantrymen to meet the demand for soldiers, and so-called demi-lancers wearing half or three-quarter armor and riding unarmored horses served in the same armies with fully armored gendarmes. Light cavalry, of course, was still indispensable for scouting and raiding.
The invention of the wheel-lock pistol around this time made the use of firearms by cavalry practical for the first time, so that by the 1550s the German heavy cavalry had abandoned their lances in favor of pistols. This led to a contest between the lance and the pistol that played out on the battlefields of the late 16th century. The old lance charge as favored by the French was conducted in the en haye ("in line") formation, which was rarely more than two ranks deep because its goal was to present a broad front to take full advantage of the charging power of lancers at full gallop. The Gendarmes on their armored horses formed the first rank, while their squires rode behind to take advantage of their protection. The Germans, in contrast, preferred the caracole formation that used the momentum of a deep column. They would ride up to the enemy and the first rank would discharge their pistols, breaking off and riding to the back so that the next rank could fire, and so on. While this worked well enough against infantry, it was less effective against a disciplined force of lancers. Having admitted that a picked and chosen squadron of pistols would kill more of the enemy than a squadron of lances, Roger Williams nonetheless claimed to have often seen German reiters flee from a determined lancer whom they outnumbered three to one, and noted that too many wasted their shots by firing at a distance and didn't charge their pistols with the right amount of power, resulting in inaccuracy or under-penetration. François de la Noue responded to this line of argument by pointing out that lances were only really good for wounding horses and became useless after the initial charge, while the second and third ranks of lancers wouldn't even get to use their lances before they had to drop them and draw their swords in the melee. In contrast, if the pistoliers were disciplined enough to hold their fire until they were at point blank range, they would wound their opponents by shooting them in the face or thigh. They also became more effective when, after firing their pistols, they drew their swords and laid into the enemy instead of wheeling off. A combination of the pistol and a modified caracole formation helped the Protestants to repeatedly defeat the Royalists and Catholic League lancers at the end of the 16th century, which helped to demonstrate the tactical superiority of the pistol when used correctly.
Due to the expense and increasing weight needed to make bullet-proof armor as firearms became more effective, fully armored knights had more or less been replaced by the 1640s with sword-and-pistol wielding cavaliers wearing a leather buff coat, cuirass, open helmet, and left hand gauntlet. During the English Civil War the cavalryman was the bane of the infantry on the flanks; the side which gained cavalry dominance generally won the battle as the losing side's infantry were trampled from behind. (Unless the winning side's infantry had already conclusively decided the infantry battle, leaving the cavalry nothing to ride down.) Gone, however, were the days of cavalry being able to break up an infantry formation on their own; faced with disciplined pike and shot the cavalry couldn't do much more than harry the infantry with pistol shot. Also notable in this period was the development of the dragoon: infantry who rode into position before dismounting and fighting on foot. They were named after their distinctive firearms, but known for their speed.
Cavalry continued to develop as time wore on, but it never regained its supremacy. Horsemen could still be dangerous; during The Napoleonic Wars infantry needed to form a special square formation in order to prevent cavalry from overrunning their lines, and during the Crimean War incidents such as The Charge of the Light Brigade showed that even when supposedy completely outclassed, the cavalryman could still achieve their objectives (despite the horrific losses the cavalry did actually manage to take the guns; they merely failed to hold them. British cavalry were scary, scary folk.) In the same battle (the Battle of Balaclava) however, the "thin red line" incident demonstrated just how vulnerable cavalry could be when taking on disciplined infantry directly; a mere regiment of British soldiers, the 93rd Sutherland Highlanders, backed up by Ottoman infantry, probably numbering between 400 and 650 men (remember the regiment would almost certainly have been under-strength) routed a Russian cavalry charge of 2,500 soldiers.
Cavalry began a swift decline in pitched battle after the Crimea, but it was still used heavily after the war, though depending on the country, its role had shifted away from an emphasis on battlefield shock. In the U.S. Civil War it was used primarily for raids on enemy supply lines, flank harassment, reconnaissance, and screening. Confederate partisan (guerrilla) bands on horseback operated behind enemy lines and undermined Union control of captured territory. Nathan Bedford Forrest was a master at this and his cavalry terrorized Union detachments. However, it was used less often in conventional battle, where cavalry units were instead typically used as mounted infantry. Cavalry did play a crucial role at Gettysburg, but more for their repeating rifles than their mobility. In 1865, Union General James H. Wilson conducted a cavalry raid where he led 13,480 troops and struck 525 miles into the heartland of the enemy. During the Franco-Prussian War, Prussian cavalry made a successful charge at the Battle of Mars-la-Tour, albeit at a heavy cost in "Von Bredow's Death Ride". After the war advocates of the mounted charge would use Von Bredow's Death Ride as a vindication of their ideals. During the 1877 Russo-Turkish War, a unit of dragoon-style cavalry (and other attached arms) led by Russian General Iosif Gurko acted as a forward detachment to support the advance of a parent formation, by seizing key positions in the enemy's depth, collecting information, destroying rail and telegraph lines, and sowing panic in the enemy rear.
Both the Russians and Japanese used cavalry in the Russo-Japanese War. The Russians relied on their Far Eastern cossacks in Manchuria, which did not achieve the same level of effectiveness as their European counterparts (in spite of a 6-1 numerical advantage in horsemen). One cavalry raid was carried out by General Mishchenko in early 1905 when an ad-hoc grouping of 7,000 cavalrymen was sent to attack a Japanese supply dump within the enemy rear. It failed to achieve its objectives due to a loss of surprise and the lack of mobile firepower. The Japanese trained their cavalry much like in European armies, but the war brought changes to their employment methods. Japanese cavalry generally found itself outmatched in mounted combat by the Russians, such as the action at Wu-chia-tun on 30 May 1904 where cossacks outmaneuvered and defeated General Akiyama's 1st Cavalry Brigade. The Cossacks were forced to withdraw with the arrival of Japanese infantry reinforcements, but the cavalry battle caused a change in Japanese cavalry employment to prevent exposing them to the Russians in mounted combat; they were subsequently used more as mounted infantry and with the closer cooperation of infantry.
The last incident of cavalry being seriously deployed was during the First World War, when the first engagement of the conflict involved a small group of British lancers encountering a group of opposing German cavalry; an inconsequential early victory for the British in what was to become a war characterised by the futility of charging prepared machine gun positions. War, from that point on, was to be decided by the tank, the infantryman, and the artillery shell, and especially the plane, and the era of the cavalryman drew to a permanent close.
That said, The Polish-Soviet War and the Russian Civil War before that, had considerable use of cavalry / dragoons. In general Eastern Europe was more cavalry country than the West due to the increased geographical size of the East and the lower density of fighting soldiers per kilometer of front, and the age of the cavalry reached its conclusion later there.
All that said, mounted cavalry has continued to be used off-and-on into the 21st century, though later examples end up being cases of Schizo Tech (the civil war in Afghanistan before the Americans invaded featured images such as men riding horses and carrying AK-47s). If you lack easy access to motor vehicles or aircraft, but you have horses, their mobility advantages still apply. During the early days of World War II, the Poles had an anti-tank rifle that could be transported on a horse and quickly removed and set up for firing. It would be more accurate to say that horses can be used in some modern situations as dragoons rather than cavalry. The difference being that while a Cavalry trooper is trained to fight from horseback, Dragoons are trained to fight on foot, mainly using the horses to quickly get near their objectives (although around the 18th century, the word "Dragoon" evolved to mean "Light Cavalry"). Another interesting note is that some police departments at least in the United States still maintain provisions for horseback duty, in part because horses are easier and quicker to maneuver around in urban environments, especially if the roads are rendered impassable to most vehicles.
Also, it is a common spelling error to refer to men riding horses in battle as "Calvary". Calvary is a hill in Jerusalem. Easy way to remember the spelling: In the war movies, you always hear them talk about "Armored Cav" or "Airborne Cav", or talk about "Cav Troopers". Never "Cal".
Lastly, it should also be remembered that not all cavalry was based around the horse. Desert regions saw the use of camels, where their slower speed on solid ground was out weighed by their ease at negotiating sandy terrain, and the easy logistics provided by their water hoarding abilities (of critical importance in the desert). Camels were also known to terrify horses who aren't used to their distinctive odor.
Elephants also saw action, essentially being used as super-heavy cavalry. Despite lacking any real finesse and not being particularly maneuverable, their size allowed them to either house multiple archers as opposed to the horse's one, a single heavy weapons platform (usually a ballista), or alternatively, just trample over the enemy lines. Elephants did however suffer from the disadvantage of turning and fleeing from certain sights (usually incendiary weapons) or upon injury—this is why each war elephant had a man seating on the back of its neck with a hammer and stake to put the beast down should it panic; if this man was incapacitated and elephant somehow spooked, it was not rare for it to make a U turn and trample its own lines. Due to this weakness, Alexander the Great used his Indian elephants for logistics only. In the regions where elephants were available, they eventually fell from grace as gunpowder weapons improved, even before the horse, and they just served as a big target. Alexander's Successors made heavy use of elephants; this seems to have been because they had come to a stalemate with opposing armies organized like themselves and were searching desperately for a game-breaker. It could also be because elephants were simply impressive, a weakness monarchs the world over have always had. Romans however never particularly favored elephants and usually found ways to counter them. The Carthaginians, as is well known, did use elephants. The general Hannibal Barca is famous for taking elephants over the Alps. However this fame is from the determination and engineering skill required for the feat, and it's sheer eccentricity. What is little mentioned is that few of these elephants were in fighting condition by the time they reached Italy and these didn't last long.