The proverb is of either ancient Arabic or Chinese origin, but the closest you're going to get to a Trope Namer is Niccolò Machiavelli, who coined this principle: The neighbour is the natural enemy; hence the neighbour to the neighbour is the natural ally.
Another proverb, which provides the Alt Title for this trope: "War and politics make strange bedfellows." Usually quoted with either war or politics mentioned alone, as appropriate for the situation.
Business and Commerce
Companies like Google and Microsoft have always had their conflicts. But as soon as bills like SOPA showed their fangs? Suddenly, the entire internet was united to fight back. Whether the companies fight for freedom or money is unknown, but no one seemed to care anyway.
Automotive example: Holden and Toyota teamed up to produce the Holden Commodore VR and the Toyota Lexcen. However, the Lexcen was not a export model, but solely an Australian version of the Commodore, but without the Commodore's big, brash, American V8 engine, instead only getting a Buick V6 engine. This was created so Toyota had a rival for the Ford Falcon (apparently the 1991-1995 Toyota Camry, incidentally, this was sold as a Holden too, the Holden Apollo being roughly the same size as a BMW 3-Series), a big car, and one of the Asia-Pacific region's biggest sellers. Needless to say, General Motors' (owners of Holden) alliance with Toyota ceased in 2005.
The world of high-end electronics works in weird ways. Building a chip fab is eye-wateringly expensive and complicated, and thus there is a limited amount of enterprises in the world that can build advanced processors, memory and what have you. Also, high-level research is expensive and time-consuming, so the few really successful designs tend to stay dominant for a while and be licensed to everybody. As a result, strange collaborations spring up.
Pentax and Sony have long been rivals in the budget-conscious DSLR market (the primary market being squarely dominated by Canon and Nikon), but from the K-x onward Pentax has stopped using its own sensors and uses Sony ones under license.
For a long time Apple used Samsung-provided memory and screens, despite Samsung being their most dangerous rival on the market. This particular relationship ended sourly when Samsung proved more dangerous than at first thought, and Apple started a string of expensive legal proceedings against them. Samsung said "well, fuck that" and is no longer making much of anything for Apple.
Apple and Samsung also have a common Enemy Mine: Qualcomm (who produce system-on-chip, or SoC, platforms for tablets and cellphones). The former needs them for cellular modems and the latter uses their chips for US versions of phones, even though they have their own SoC.
In the midst of a certain ugly and rather scandalous dispute between CBS and Time Warner Cable, TWC's biggest competitors voiced their support for TWC against CBS's underhanded and consumer-unfriendly anti-TWC tactics.
Infamous American gangster "Lucky" Luciano bargained for his release from prison after claiming that he could protect American wharfs from saboteurs with gangster muscle. Some people suspect that it was actually Luciano's men, if anyone, who were causing the problems in the first place.
Luciano also supposedly made available contacts in Sicily to military intelligence during the Italian campaign, a claim that he also later denied. Given that the Fascists intended to wipe the Mafia out, the claim has some credence. This also surfaced with the invasion of France, where the Corsican Mafia agreed to provide intelligence in return for the US overlooking their drug operations to American ports. This developed into the "French connection" of infamy, and the relationship between the Corsican Mafia and CIA later proved useful for using them as local "muscle" to bust the French Communist-run dockers union when they struck in Marseilles, preventing the US shipping needed military supplies over to help France hold down Vietnam (not that it worked forever anyway).
Gang bangers in small cities have been know to team up against police and non-local gangs moving in then go back to fighting each other again.
When Twilight first came along, every fandom which had ever had rivalry with Harry Potter was suddenly allied with the Potter fans against the Twilight fans.
This actually happens quite a bit in music. Some genres (such as Heavy Metal and Rap) will have people who believe that they should put aside all differences and unite against other types such as pop. Look on any YouTube music video not relating to pop music.
Rockers and rappers are also often allied against censorship that wants to make all music family-friendly.
It happens quite a bit within pop music's own fan culture world too. For example, we have the alliance forged between Taylor Swift's Swifties and Lady Gaga's Little Monsters against Katy Perry and her Katycats, after the reveal of Swift's song "Bad Blood", written about Perry. Meanwhile, Gaga was already Perry's rival as the two leading way-out-there performance artist type female pop stars.
Larry Flynt resents Woody Harrelson for his portrayal of him in The People Vs Larry Flynt, but vocally supported him when he intentionally got himself arrested for marijuana possession in protest over the law prohibiting it.
Slayer, bane of Religious Conservatives everywhere (at least in the 80's), released a pro-life song. (But see below.)
American Censorship Day had a bit of this. In particular, groups like Wikipedia, Mozilla, Reddit, and Google were fighting alongside 4chan for a common cause (though this may be more of a Rivals Team Up; nobody particularly likes 4chan, but there's little actual hostility from the mentioned groups). Republican Darrell Issa also posted a tweet noting how both he and Democrat Nancy Pelosi were against SOPA.
Minecraft and Roblox normally loathe one another, but both of them were able to come to the agreement that SOPA was bad mojo, causing a temporary redirection of their rivalry towards fighting against it.
In the 1990s, pro-Israel American neoconservatives and Islamic activists shared a common enemy in the form of Slobodan Milosevic's Serbian chauvinist regime.
Militant feminists and conservative Christians disagree on almost every issue, with the exception of one: they are both opposed to pornography. The feminists feel that it's exploitative of women, while the Christians feel that it's immoral, sinful, and exploitative.
The odd alliance between the Religious Right and militant feminists on the subjects of porn and prostitution has been frequently lampshaded and criticized by more moderate "sex-positive" feminists. There's considerable debate in the feminist camp as to whether or not sex work is exploitative, especially when the participants are fully willing.
It gets better. A proposal to create a ".xxx" top-level domain for internet porn was recently approved by ICANN, resulting in an alliance between the Religious Right (who fear that it will legitimize pornography) and much of the porn industry (who fear that it will lead to tighter regulation) against it. Alliances don't get much stranger than that.
Similar to the issue of the ".xxx" top-level domain for internet porn, both the Religious Right and the porn industry are opposed to making it legal for women to go topless. The former believe that it's immoral, while the latter... Well, they feel that it would dramatically decrease business for them — since there would no longer be a demand for "topless pornography".
Except, in several states (including New York) it IS legal for ANYONE to go topless, as long as they don't enter private businesses that request you not to (i.e. the famous "No shirt, no shoes, no service" rule).
Similarly, the alliance between militant feminists and the Christian Right in banning the wearing of burqas (as seen in France and Belgium). Militant feminists think burqas oppress women and restrict their rights, while the Christian Right tend to cite "fundamentalism" creeping into society. Although burqas are banned in several explicitly Islamic nations already, so it's a bit more complicated than that, and burqa bans create an enemy mine on the other side of the fence: religious Muslims and political liberals (in the "small l" sense of "let people do what they want within reason."
Not to mention that usually its niqabs, not burqas which are at issue. Actual burqas are very rare, and only seen widely in Taliban-ruled Afghanistan.
It seems that the enactment of Prohibition in the US was facilitated by some very strange bedfellows indeed — Klansmen allied with militant labor unions?
Islamic and Christian fundamentalists are generally opposed to each other, with the subscribing to different religions and being, well, fundamentalists. However, creationist works and arguments critical of Darwinism tend to pass between both groups, as do tracts critical of homosexuality.
During the 1800 election in the United States, Alexander Hamilton and Thomas Jefferson both decided that they hated Aaron Burr more than they hated each other, thus leading to Hamilton persuading the Electoral College to vote for Jefferson instead of Burr.
Astonishingly common in US political history, compared to other countries. In fact, both main parties were this during a great deal of their history. To make things further complicated, there often have been alliances between members of opposite parties, which sometimes lead to political realignments. Indeed, both the Whig and the Republican parties were in large part formed by different interests that teamed up in opposition to the policies of the Democratic governments of the day.
In 2006, Nigerian President Olusegun Obasanjo tried to change the constitution to allow himself to contest for a third term in office the next year. This led to a feud with his Vice President (and heir-apparent) Atiku Abubakar. To stop the amendment, Atiku teamed up with opposition leader Muhamadu Buhari who was planning a presidential bid as well. They successfully kept Obasanjo out of the race, but their alliance fell apart soon after since neither would step aside for/endorse the other. Obasanjo's new hand-picked successor, Umaru Yar'Adua, won.
Yar'Adua then proceeded to die in office, leaving the presidency to the Unexpected Successor Goodluck Jonathan, who surprised everybody by actually doing a decent job and getting elected in his own right.
In a more martial Nigerian example, imprisoned Niger Delta rebels like Isaac Boro were released by the government and admitted into the Federal Army to help thwart the Biafran secession. The Niger Deltans figured being minority ethnicities in a Nigeria with 3 mutually hostile major tribes was more palatable than being minority ethnicities in a Biafra with 1 very dominant tribe, the Ibo.
This trope has reoccurred on a regular basis throughout Canadian history:
Confederation itself was begun when the Reformer George Brown offered to serve in a coalition government with the Conservative John A. Macdonald to resolve the political gridlock that had paralyzed the United Province of Canada. Their efforts to solve the problem eventually led to the Confederation agreement that founded Canada.
The colony of Nova Scotia was bitterly divided over whether to join Confederation or not. The question was eventually resolved when the Irish nationalist Fenians, who were trying to gain political leverage with Great Britain by attacking Canada, began raiding the colony from the United States. The pro- and anti-Confederation movements were forced to team up and eventually joined Canada in no small part due to the need for mutual defence against any American raids.
On the other side of the continent, British Columbia had to deal with the same question. Along with a pro-Confederation movement, the province also had an anti-Confederation movement that wanted to stay independent and an Annexation movement that wanted to join the U.S. As in Nova Scotia, the pro- and anti-Confederates eventually came together.
During World War I, Canada was extremely bitterly divided over the issue of conscripting men to fight in the war, to say nothing of even participating in the first place. Prime Minister Robert Borden eventually overcame the Liberal opposition by enticing a number of Liberals to join him in a "Union" government that was a glorified coalition, leaving Wilfrid Laurier with a weakened Liberal rump based mostly in Quebec. Laurier's death in 1917 further crippled the Liberals' attempts to recover.
In the constitutional debates of the early 1980s, the Quebec separatist Premier Rene Levesque found common cause with seven of the other nine provincial premiers, who came together in opposition to Prime Minister Pierre Trudeau's constitutional reforms. The "Gang of Eight", as it was called, eventually forced Trudeau to put together a compromise that addressed some of their major concerns and eventually became the 1982 constitutional patriation.
The British General Election of 2010 brought about a coalition government of the right wing Conservative Party and the left wing Liberal Democrats.
Not so odd if you know a bit more about both parties. The Liberal Democrat free-marketeers (which Clegg represents) and the Conservative liberals (which Cameron represents) have more in common than difference. What has caused problems is that the broader parties don't get on and, given how the middle-class Labour support shifted to the Liberal Democrats during the 2000s, Clegg essentially gambled and is now losing much of his party's newer supporters (and doubtless some of the older ones).
This happens a lot on Internet debates about religion. Christian fundamentalists, atheists, and New Agers are all opposed to each other, yet in debates on religion, either the atheists will team up with the New Agers against the Christians, (as they think that fundamentalist Christianity is irrational) or the Christians will team up with the New Agers against the atheists (because they believe that atheists are against spirituality). For some reason, the Christians and atheists never team up against the New Age movement. This is generally because there just aren't enough things that New Agers do that atheists oppose that fundamentalist Christians also don't do, so there's a lack of common ground between atheists and fundamentalist Christians.
The reason, arguably, is that Christians are, generally, fairly ambivalent towards the New Age movement because seems fairly non-threatening and borrows from Christianity (angels, etc), and, while atheists are generally against spirituality, they may feel they have common ground with the new-age movement as its practitioners are also a minority, something that can lead them to see the New Agers as allies, or, at least, as people less opposed to their ideology than mainstream Christianity, which a lot of them kinda hate in a big way.
There is room for a Christian-Atheist alliance against new-agers. Both believe in a rule-following, relatively objective universe. Or they might think the New Agers are nuts. But this alliance is very rarely seen.
The Westboro Baptist Church, aka the "God hates Fags" church, headed by 'Reverend' Fred Phelps, has managed to piss off absolutely everyone. Their anti-gay protests drew plenty of condemnation from both the left and right, but even the most anti-gay social conseratives were shocked by their picketing of the funerals of soldiers with sings like "God killed your children". They even got denounced by the Ku Klux Klan. How low can you get?
They even got The KKK and the Hell's Angels themselves working hand-in-hand with law enforcement officers and firefighters to protect the funerals of the Sandy Hook victims from this kind of nonsense and Anonymous doxing the whole flock simply for trying to protest at those funerals.
When WBC head Fred Phelps died in 2014, George Takei declared that the most appropriate thing to do would be to give sincere condolences to Phelps' surviving family and congregation rather than protesting his funeral in retaliation. This course of action was echoed by a massive number of conservative Christian individuals and organizations who otherwise wouldn't find themselves in agreement with Takei on most issues.
National Voluntary Organizations Active in Disaster is a group of a number of organizations that are active in various facets of disaster response. The catch? Many are religious organizations from varying theological perspectives. Catholics respond alongside Protestants. Jews respond with Muslims. So do Hindus, Buddhists and the Scientologists. And- miraculously- it all works out! http://www.nvoad.org/
And then again between Catholic France and Protestant Sweden during the Thirty Years' War; once again to limit the Habsburg power. Cardinal Richelieu practically invented realpolitik. Sweden also was for a short time allied with its Arch-Enemy Denmark-Norway during the war...but then Denmark-Norway allied with the Habsburgs in the late part of the war.
You might not expect Republicans like Ron Paul and the Tea Party movement to have common cause with progressive Democrats, but they've found themselves on the same side in opposition to free trade deals and continental integration. The Tea Party and its supporters see these trade deals as a threat to the sovereignty of the United States and government interference in international trade (many Tea Partiers would prefer to simply have no rules or regulations on trade at all), while their progressive allies see the trade deals as leading to jobs being offshored and labour standards being weakened in America itself.
The sovereignty issue is a sticking point for many left-wing nationalists in Canada as well. The progressive Council of Canadians has found itself on the same side as right-wing border groups like the American Minutemen, both of whom see continental integration as a threat to their countries' sovereignty.
Ron Paul and a number of Tea Partiers have also found common ground with the left-wing Occupy Wall Street, particularly over corporate welfare, Wall Street bailouts, foreign wars, and marijuana legalization.
Most recently, there are those on both the left and right side of American politics that have united in opposition of President Obama's use of drones in warfare, particularly his failure to rule out using them on Americans on American soil!note Of course, nobody remembers that the "on American soil" bit was limited by the caveat "...to take pictures." Creepy, but not Death from Above.
In street demonstrations against Israel, the crowd will often include fundamentalist Muslims, anarchists, neo-Nazis, ultraliberals, and anti-Zionist Hassidic Jews who believe the Messiah must come before Jews return to Israel.
It is interesting that on the old Israel Insider website - a very partisan propaganda site for Israeli expansionism - many comment pieces were written by Northern Irish Unionists/Loyalists, including a regular commentator known for his association with extremist Loyalist factions. The particular loyalist grouping this commentator was associated with had strong links to far-right groupings such as Column 88 and the National Front, organisations hitherto not renowned for being pro-Jewish or sympathetic to Israel. The reasoning appeared to be both parties involved drawing parellels to a terrorist threat (the IRA/Hamas) drawn from a subject population who knew no better than blind hatred and violence towards their neighbours who were treating them with nothing other than forbearance and kindly understanding, despite all provocations. What Israelis or Ulster loyalists might have done to alienate and disaffect their neighbours was never spoken of, but the strong implication was that the two terrorist groupings were working together as a threat to world civilisation.
Ronald Reagan seemed to be a fan of this trope, and in fact saw it as a potential avenue toward world peace. He once made a speech in which he wondered how much better the world would be if space aliens invaded, thus forcing the US and the Soviet Union to put aside their differences and fight the threat together. He felt this would remind both sides of their shared humanity, and lead to an end to human conflict. Lest you think he was joking, he actually brought up this scenario in several speeches, including one to the general assembly of the United Nations.
Another great example from history is the Catholics and the Protestants for teaming up against the Anabaptists. In the end they took back the city of Munster and then called it a day for their alliance and begin to promptly fight one another again.
Prominent religious conservatives and liberal disability rights groups have teamed up several times to fight the legalization of assisted suicide. They were also on the same side during the Terri Schiavo debacle.
Following the passage of Proposition 8 (which outlawed same-sex marriage in California), Several families sued the state on the grounds that the referendum was unconstitutional. The attorneys who teamed up to represent them in court were Theodore Olsen and David Boies, best known for arguing opposing sides of Bush v. Gore. Needless to say, the Defendants didn't stand a chance.
The pro-life movement includes numerous groups arguing from different angles, many of whom wouldn't usually agree with the religious conservatives traditionally associated with the movement. Staunch atheists, self-styled liberals, American Democrats and feminists of various kinds have all been known to team up with them.
Jane Hamsher, creator of the liberal blog Firedoglake and Grover Norquist, conservative kingmaker, teamed up in 2010 to oppose the Affordable Healthcare Act. The conservative argument was that it was big-government socialism, while liberals believed that it didn't go far enough.
Hunters and animal-rights activists may not always see eye to eye, but they will team up to oppose development projects and save endangered species.
In issues involving the Separation of Church and State in the U.S., atheist groups and religious groups do team up. Some Christians don't like government being linked to their religion, the Jews, Muslims, Buddhists, and other groups don't like Christianity being endorsed by the government, and atheists don't want any religion endorsed by the government. The group Americans United for Separation of Church and State is an example of this. Another good example is the opposition to Amendment 8 in Florida, an amendment to allow the state treasury to be used to support churches and religious institutions. One of the more prominent opposing voices is a Rabbi.
In the midst of the 2012 Chick-fil-A gay marriage controversy, Chick-fil-A's supporters (during the "Chick-fil-A Appreciation Day") and its protesters (including the "kiss-in" folks) joined in condemning the mayors of Boston, Chicago, and Philadelphia for comments indicating that they would work to block the fast food company's plans to open restaurants in their cities. Both sides of the issue maintained that you can agree or disagree with the company's stance all you want and protest one way or the other accordingly, but to dictate that someone cannot operate a business somewhere because of their views would be an infringement upon free speech and free markets.
Despite their obvious theological differences, Catholics and Protestants often team up to oppose abortion.
Opposition to Barack Obama's efforts to enact military action against Bashar al-Assad for using chemical weapons against Syrian civilians came to be made up of Tea Party Republicans, anti-war Democrats, and numerous other constituents of both parties. On the flip side, President Obama got some support from people who don't tend to agree with him on most other issues (e.g. John McCain and Bill O'Reilly).
This all fell apart though when Obama leapt on Russia's offer to help get rid of Syria's chemical weapons. The anti-war Democrats and non-interventionist Republicans were cool with this, as were many Democrats who had favored military action (since it was a way of ending the chemical weapons issue without fighting), but the pro-war Republicans were more than skeptical and the Tea Partiers shared in the skepticism of Russia's intentions and were opposed to the existence of any US role (also: it made the UN look useful. Tea Party hates that).
Certain factions of the feminist movement have a strong distaste of the colour pink, as do manychauvinistic dudebros. This irony is not lost on some of the moderate branches of feminism who believe that rejecting the concept of prescribed gender roles is not the same thing as rejecting anything considered "feminine" - and that hating pink (for reasons other than simple personal preferences) can be misogynistic itself.
While it was obviously something that conservatives were angry about, even liberals and other people who dislike Sarah Palin were disgusted by Martin Bashir's assertion that she deserved to be subjected to "Derby's dose" (a punishment enacted on African slaves where they were forced to consume feces) for comparing the federal debt to slavery. This was compounded with Bashir's fellow former MSNBC anchor Alec Baldwin alleging a Double Standard in the fact that Baldwin was quickly fired for an anti-gay slur he said in an outburst against reporters yet Bashir still had his job after his scripted offensive comments. Unsurprisingly, Bashir eventually resigned.
This is how Sweden was founded. Western Geats, Eastern Gaets and Swedes (viking-tribes) teamed up to avoid being conqured by the Danes. To this day their national emblem is "The Three Crowns".
Despite having very sour relationship between Israel and Saudi Arabia (since they don't have emissaries to their respective countries) and Saudi support for many Palestinian groups, both countries found themselves to be unlikely allies against a great threat, Iran, due to the concerns of the Iranian nuclear program.
The "Robbers' Cave" experiment. Two groups of boys at a summer camp were first isolated from each other and encouraged to form a group mentality. After a few days they were introduced to the other group in a competitive environment in order to produce inter-group friction. This stage was ended early when the hostile rivalry reached potentially dangerous levels. The groups were then given mutual "superordinate goals" forcing them to work together, and the hostility evaporated as quickly as it had appeared.
Fans of sports teams coming down to the wire on that last playoff spot can find themselves rooting for their most hated rival to win because their rival just happens to play some third team that needs to lose in order for their team to be able to jump ahead of them in the standings. "(Insert Hated Team Here) Fan For A Day" signs are not uncommon in the stands in such games.
A funny example in 2014 FIFA World Cup: Germany defeated the host country, Brazil, for a spectacular 7-1 in one of the semifinals, which was the worst defeat Brazil ever suffered and a traumatic experience for all the fans. At one point the Brazilian fans (those which hadn't left already during the first half) was cheering on the German team. The other semifinal match was Netherlands X Argentina, with the latter winning and making it into the finals against Germany. Nearly ALL Brazilians rooted for Germany, out of spite and fun. And Germany scored 1-0 during additional extra time, thus winning the tournament. Brazilian fans were satisfied, even after losing 3rd place match to Netherlands, just because the arch-rival Argentina was defeated. For those not familiar with soccer, Brazil vs. Argentina is probably the greatest rivalry in the world of soccer - to the point that there is a Cup that only these two national treams dispute! It also helped that this was only the second time Germany and Brazil meet in a World Cup, and the German team won fairly gracefully, toning down the goal celebrations at one point and comforting members of the host team after the game. Plus, loosing so badly is already a disgrace, but loose so badly against team which then doesn't move forward to win the cup can be considered as even worse.
Heading into the last game of the 2014 Six Nations Championship, England were to be the champions if France, England's longstanding rivals, won against Ireland. English fans on social media commented on how odd it feels to be cheering on France.
Such sporting rivalries have given rise to the popular "I support two teams - X, and anyone playing against Y" T-shirt design, with many regional variations.
There are a couple of football rivalries in Germany, the most famous being the one between Borussia Dortmund and Schalke 04. Those matches are always heated. But there are two moments during which the audience is always in agreement: When the "Steigerlied" is played (a song regularly sung in both arenas to honour the time when the Ruhr Valley was a coal region) and whenever Bayern München is loosing. It's a very common attitude among most football fans in Germany to cheer even for the worst rival as long as Bayern München doesn't get a point.
The American Revolution was a classic example of this. The revolutionary republican American forces were assisted (arguably decisively) by troops and naval power supplied by France, at the time a very conservative near-absolute monarchy. It was deeply ironic when radical republican ideology crossed the Atlantic a couple of decades later and overthrew that same monarchy.
More ironic still is that the United States considered their previous alliance with France voided by the revolution, and the two countries very nearly went to war.
Napoleon's regime is an example of this in an ideology. Napoleon was a veteran of the French Republic's military, his government used the republican flag and he claimed to embody the ideals the republic had represented and yet his government was unashamedly an absolute monarchy with Napoleon not shirking even slightly from the trappings of royalism (see, for example, the painting of his coronation).
It gets even better. To this day, both Bonapartists and legitimistsnote Yes, they still exist are considered the far right in France, so they are united by their mutual disdain of democracy.
In the War of the Triple Alliance, Brazil and Argentina, who had long been antagonistic towards one another, went to war against Paraguay. They were joined by Uruguay, which was basically their punching bag.
World War I
During World War One, the conservative monarchist German government helped the radical Vladimir Lenin return to Russia so that he could overthrow the government and make peace with the Central Powers.
Also during World War I, progressive Britain and France were in an alliance with autocratic Czarist Russia against semi-democratic Imperial Germany. When the U.S. was thinking of entering the war, Russia's February Revolution happened and the Wilson administration welcomed the development as removing the last obstacle to a "democracy vs. dictatorship" narrative.
The Soviets and Nazis declared a nonaggression pact, though both considered it merely a stalling action before war broke out. Germany broke the treaty first and attacked.
Specifically Germany wanted the USSR out of the way so that they could defeat Britain and then attack the USSR because they wanted to avoid a two-front war. The USSR wanted to wait as long as possible so that they could get their factories and army up to full capacity. Obviously Germany never took Britain and attacked the USSR before they were entirely ready (and also allowed itself to get sidetracked by a mission to clean up the mess Mussolini had made in the Balkans), thus causing a two-front war anyway.
Part of the Nazis stated policy was to a) destroy the Communist threat to the German state and b) annex, ethnically-cleanse and settle the Slavic lands as part of the ideology of obtaining 'Lebensraum' for ethnic Germans. It is very unlikely that Hitler ever intended to honor the pact.
Actually, Stalin knew that. He believed that Germany would eventually invade the USSR. The reason he entered the non-aggression pact was to buy time to prepare for the invasion.
There is evidence that at one point Germany offered to let the USSR join the Axis, but the USSR wanted too much in exchange (control of Finland, Turkey, and eventually the Persian Gulf). Plans to invade the USSR were drawn up soon after.
In Mein Kampf Hitler declares his intention to conquer the USSR. It appears that the Soviet Union was the only place where it was read.
The United States, Great Britain, China, and the Soviet Union worked side by side to defeat Germany, Japan, and Italy
Winston Churchill was a staunch anti-Communist, but he promised help to the Soviet Union immediately after Hitler attacked it. He once said, "If Hitler invaded Hell I would make at least a favorable reference to the devil in the House of Commons."
Various people classified as sub-humans by the Nazis, such as Slavs, Chechens and Indians, teamed up with the Nazis against a common enemy (the Soviet Union for Chechens, Britain for Indians). Many Slavic people actually served in the Wehrmacht itself.
Only a very small number of Indians sided with the Axis, and were generally of little consequence.
Complicated further by Hitler never wanting to go to war with Britain. In fact it's been suggested that he originally wanted an Anglo-German alliance and he initially admired the British for their military and empire-building capability. Had Edward VIII remained on the throne, this could've likely happened, or at least, Hitler thought so, and wondered What Could Have Been if he had.
It's a reasonable thought for him to have had. Politics makes strange bedfellows was literally true in the European ruling houses, most of whom were actually related to each other. Eddie's great-grandfather was German; the Duke of Saxe-Coburg and Gotha. For that matter, the English royal line stemmed from George I, who prior to becoming King had been the Elector of Hanover, and both he and his son (George II) were German speakers who grew up in Germany. Edward VIII's pro-Nazi leanings were likely the real reason he was hustled off the throne; Wallis Simpson was just the excuse.
The real reason it took the Nazis so long to bomb Britain is because Hitler admired the country enough to not want to destroy it. He offered Churchill numerous offers of peace, all of which were turned down. And while Hitler always intended to invade the Soviet Union, the reason he did it earlier than expected was in hopes that if he could crush Russia, Britain would be intimidated into surrendering. Had many other countries not gotten involved, this might have worked.
Not to mention that in World War One, Italy fought on the Allied side. It thus wasn't inconceivable for switches to happen.
For the Slavs to get around the cognitive dissonance, both Himmler and the Croatian puppet government with its Axis sympathizers agreed that Croats (Baltic Slavs in general by their definition of Croat), whether Catholic or Muslim (but not Orthodox or Jew) were not Slavs at all, but Aryans who happened to speak a Slavic language. This is why certain Slavs were allowed into the German military. Western Ukrainians, still angry about Stalin causing the worst cataclysm in their country's recorded history, also supported the Nazis in significant numbers (though far more joined the Red Army). Despite their common perceived enemy of the Red Army, the Nazis would not overlook the Ukrainians' Slavic "race" for long and paid them back with betrayal, so the Western Ukrainian support turned away from the Axis.
In Yugoslavia, the Croatian Ustase fascists (who routinely massacred Serbs) and the Serbian Chetnik fascists (who routinely massacred Croats) teamed up in order to fight Tito's Communist partisans.
Perhaps the strangest of bedfellows during WWII were Nazis and Jews. Nazism and Zionism had a common goal, that being the removal of Jews from Europe. So during the early days of the NSDAP, one of the biggest financial contributors was a Zionist organization. After the Nazis were firmly in control of Germany, they began funding Zionist programs to ship Jews off to Palestine. For three years, Zionists were even working directly with Reinhard Heydrich to achieve this.
Zionists were among the groups of Jews that an exception was made for, when it came to which Jews were to be sent to concentration camps. Also, the Nazis banned all other political parties in Germany, except for the Zionist Party.
Another instance of Nazis and Jews working together was the Wehrmacht allowing Jews classified as "Mischling" (Germans who were only half or one-quarter Jewish) to fight for the Third Reich. The reasons for why these people wanted to fight for Nazi Germany was varied. Some of them were able to use their military position to protect their Jewish relatives from being persecuted. Some were Zionists who approved of Nazism. Others were simply patriotic Germans who, while part Jewish, still blindly supported their country. And finally, there were both Mischlings and Slavs who, while knowing they were considered inferior by the Nazis, still considered the Soviet Union to be the far greater evil.
The Judenrat (Jewish council) were administrative bodies that Jews were required to form in territory occupied by the Nazis. Many of these councilors worked with the SS directly, including in the process of liquidating Jews. Today the role of the Judenrat in the Holocaust is very controversial. They're either seen as opportunists who sold their fellow Jews out, or people who were forced into that role by the Nazis out of fear.
During the Battle of Britain, the British and Irish governments put together a joint plan, Plan W, for the defense of neutral Ireland against German invasion. One effect of this plan was the Irish military trading in their uniforms (which resembled those of the Germans) for new ones more closely resembling those of the Brits, to avoid spooking jumpy British troops from shooting at the wrong people.
Worth noting, at the same time, the Irish also had plans in place for fighting off a British invasion with German assistance. Ireland's strategically valuable location meant they could not afford to assume either side would have qualms about invading if it meant launching or averting an invasion of Great Britain.
At one point Italy switched sides, giving birth to multiple cases of this: the Italian government was on the same side as the Allies, who were the enemy until literally the day before, due to German troops seizing control of most of the country; in German-occupied territories, La Résistance was divided into four factions (Monarchists, Republicans, Communists and Anarchists), with each faction loathing the others but agreeing to collaborate and settle things peacefully after the war and Germany's defeat and king Vittorio Emanuele III (detested for allowing Mussolini's takeover and abandoning Rome and the armed forces without orders right after announcing the surrender to the Allies, even before the Germans moved to take over); and the Italian Resistance occasionally collaborated with the Italian Fascists (allied with the Germans) against the Yugoslav Partisans to try and defend the Italian population in Istria (a border area inhabited by both Italians and Yugoslavs, where Mussolini's government started throwing Yugoslav civilians into camps and the Yugoslav Resistance had recently started doing the same to the Italians); and the Communist faction of the Italian Resistance would occasionally collaborate with the Yugoslav Partisans against the Monarchists.
The Italians (Benny the Moose himself included) were actually pretty anti-German and anti-Hitler prior to the late 1930s. In fact, the British and French joined Mussolini's Italy in the Stresa Front, an agreement to uphold the independence of Austria and prevent any further breaking of the Treaty of Versailles. Mussolini himself referred to Hitler as a "mad little clown." However, the second Italy invaded Ethiopia, the British and French lost what little friendliness with Mussolini they had and took steps to isolate his country. (Most of their measures, including a toothless embargo on weapons sales, didn't work.) Without any friends, Mussolini and his Fascists were forced to cozy up to Hitler and the Third Reich. (That was a fatal mistake.) This may have contributed to the stereotype of the Italian forces being cowardly, when actually they were merely chronically unmotivated to fight. If the people you've just been ordered to kill are the people who were your allies last week, dropping your rifle and just getting the hell away from all this madness is not at all an unreasonable response.
Five days before the death of Adolf Hitler The Battle for Castle Itter was fought. Dubbed the strangest battle of World War II; 14 American soldiers, two Sherman Tanks,French and Eastern European prisoners, Austrian Resistance, as well as ten anti-nazi Wehrmacht soldiers and one Waffen-SS man teamed up together to drive elements of the 17th Waffen-SS Panzer Division from setting up a stronghold in the castle. Notable prisoners included tennis star Jean Borotra,former prime minister Édouard Daladier, Charles de Gaulle's elder sister Marie-Agnès Cailliau,former commander-in-chief Maxime Weygand, former prime minister Paul Reynaud,former commander-in-chief Maurice Gamelin,right-wing leader François de La Rocque and trade union leader Léon Jouhaux. Besides the French VIP prisoners, the Castle held a number of Eastern European prisoners detached from Dachau. Major Gangl of the Wehrmacht managed to get a a call out to a friend who owed him a favour and a group of Austrian resistance men as well as several more Wehrmacht men joined in the American/German/French/Austrian defense. Together they drove off the Waffen-SS until they were relieved by approaching US 142th Infantry Division.
During the Cold War, this was practically official policy for both sides.
In an ideological level Fascism and capitalism joined together (or more accurately, Capitalism put in fascism) in Latin America against the Communist threat. An exact opposite of what took place in WWII: Communism and Capitalism vs Fascism.
During and immediately after World War II, anti-Japanese sentiment was very strong in America. All that was forgotten when the U.S. jumped at the chance to make Japan a capitalist ally against the People's Republic of China, North Korea, and the eastern part of the Soviet Union.
Under Stalin, the Soviet Union had regarded all non-communist countries as enemies, but Khrushchev began a policy whereby any left-wing or anti-western regime in the third world could be regarded as a potential ally.
The U.S. even went so far as to support anti-Soviet communist regimes, such as Yugoslavia and (eventually) the People's Republic of China.
The Suez Crisis was a weird aberration when both the U.S. and U.S.S.R. took a hardline stance against the intervention into Egypt and both put pressure on Britain, France, and Israel to pull out. This created an instance where the U.S. voted with the Soviet Union and against its NATO allies at the United Nations. And this was at the same time that the U.S. was vehemently condemning the Soviets for crushing the Hungarian Revolution too!
The Iranian Revolution brought together (for a brief period of time) leftists, communists, and fundamental Islamists.
Also during the Iran–Iraq War, Iran received a great deal of weapons and aid from Israel, because both countries considered Saddam Hussein a far greater enemy (Hussein in fact disseminated a notorious pamphlet written by his father-in-law titled "Three Whom God Should Not Have Created: Persians, Jews, and Flies"). Historian Trita Parsi has also claimed that Israel's bombing of Iraq's nuclear facility at Osirak was assisted by Iranian intelligence, but Iran officially denies this. On the Iraqi side, the U.S., Soviet Union, gulf countries, and a variety of other countries, all gave more support to Iraq than Iran.
This tendency was also repeated again in the African countries of Chad and Somalia, when the warring forces teamed up to kick out the foreign invaders. In Chad's case, the government and rebel forces united to fight the invading forces of Libya, while the Somalis temporarily put their civil war on hold to kick out the United Nations force sent to restore order after the collapse of the dictatorship, before they returned to fighting among themselves.
The ongoing problem of piracy near the coast of Somalia has occasionally forced the naval forces of countries that would otherwise be enemies to invoke this trope by fighting together in skirmishes against the Somali pirates. A notable example of this was seen when the crew of the American USS James E. Williams fought alongside North Korean sailors to defeat pirates who had captured a North Korean cargo ship in late 2007.
Though they have yet to actually team up in a war, the Kurds and the Armenians, formerly bitter rivals, actually have somewhat friendly relations now that the Kurds and the Turks are enemies. A representative of the Independent Kurdistan movement even apologized for all Kurdish involvement in the Armenian genocide.
The best part is that the atrocities were done mainly by ethnic Kurds, not ethnic Turks. Which makes sense, since they live next to each other.
The September 11 attacks brought a few of these out of the woodwork, as governments who aren't exactly known for their fondness of the American government condemned the attacks and the terrorism that caused them. Among these governments? Iran, North Korea and the Taliban. (At least officially.)
Didn't stop the latter from housing Osama bin Laden, though...
Some commentators have suggested that The War on Terror might help bring an end to the lingering Cold War mindset between the U.S. and Russia. After all, both countries are engaged in wars against Islamic terrorists, right? So far, it doesn't seem to be working.
If anything, end of The War on Terror saw the United States slip back into a state of Cold War, and they now find themselves on the opposite sides of various proxy conflicts (notably the Syrian Civil War).
Since September 11th, Islamic fundamentalists have found sympathizers on both the far-right and the far-left of western politics. Islamic fundamentalists and the far-right are united by their anti-Semitism. In the words of neo-Nazi Billy Roper, "The enemy of our enemy is, for now at least, our friends. We may not want them marrying our daughters, just as they would not want us marrying theirs. We may not want them in our societies, just as they would not want us in theirs. But anyone who is willing to drive a plane into a building to kill Jews is alright by me." Meanwhile, Islamic fundamentalists and the far-left may disagree on almost everything else, from women's rights to the separation of church and state, but they're united by their shared opposition to what they see as western imperialism. The latter has played out on the international stage, with the alliance between socialist Venezuela and theocratic Iran.
Today, with ISIS terrorizing Iraq, a very odd alliance has cropped up with American airpower working alongside Iranian tanks, both coordinating with Kurdish rebels- the same people Iran had been fighting in their own northern territories before. ISIS seems to be Eviler than Thou from Iran's perspective, and the U.S.A. just doesn't want ISIS to win.