Divided We Fall in Anime and Manga.
- In Episode 11 of Attack on Titan, Pixis tells Eren a story about how humanity used to bicker and fight wars until the Titans showed up and was supposed to force them to unite together against a common enemy. Eren has heard that legend before and thinks it's naive because humanity still hasn't banded together. Pixis agrees with him. He tells Eren that humanity does need to stand together soon, or they would all be wiped out eventually by the Titans.
- In Code Geass, Lelouch and Suzaku want to end Britannia's tyranny. They also happen to be best friends. Unfortunately, Lelouch uses ruthless tactics to get results for the Japanese, while Suzaku believes that Britannia can be reformed with patience. Lelouch's best schemes are too often foiled by Suzaku's ace piloting at the worst possible times, and Suzaku is being used as a pawn by Britannia's corrupt nobility. Eventually, Lelouch is expelled from the Black Knights due to a brutally effective frame-up / exposition combo ploy by Schneizel. Meanwhile, Suzaku realizes he effectively became the very Britannian nobility he spent his whole life opposing and defects to Lelouch. Schneizel believes that two bitter rivals teaming up will still be a fractured allegiance that can be defeated with the combined forces of Britannia's warhead science division and the Black Knights. He's dead wrong.
- Also, the Black Knights leaving the JLF to dienote . Nightmare of Nunnally takes this one step further into Zero and Kyoto flatly selling them out.
- Britannia made a back-deal with the Chinese Federation's leaders to assimilate them into their empire, but quickly reneged on the deal once it became apparent that the whole country was in a complete anarchic riot. This rational act eventually leads to the total collapse of Britannia, because they unwittingly left one of their key assets in China undefendednote .
- Averted in Death Note: while Mello and Near start out as enemies (at least, from Mello's perspective), and when Mello visits the SPK headquarters he uses a hostage and is held at gunpoint, but instead gives him a vital -if cryptic- piece of information about Kira.
- At least twice in Dragon Ball Z, Vegeta would deliberately allow the Universe-Destroying Abomination Of The Week to power up so he could have a "worthy" opponent to fight —even going as far as to battle his own allies to let it happen. First, he did it in the Cell Saga, where he stood back while Cell attained his "Perfect" body, then battled Trunks, his own son, when the latter tried to stop it. In a later arc, when he and the other Z fighters raced to avoid the awakening of Majin Buu, he let the magician Babidi empower him with a malevolent sigil, and forced Goku to battle him instead of helping save the world. Gohan and the Kaio-Shin were left to try to stop Buu on their own. Naturally, they failed, since Buu absorbed the Battle Aura shed by Vegeta and Goku in their duel.
- This is the reason the Free Planets Alliance falls in Legend of the Galactic Heroes: selfish bureaucrats are in charge and too busy making themselves look good and make sure the military cannot take over to effectively support Yang and the competent members of the FPA Star Fleet, and in fact would even sabotage them if 'unreliable' officers (that is, people who weren't professiona asskissers) appeared to gain too much following in the public and send the fleet on suicidal missions to bolster their own prestige. This came to a head when admiral Greenhill and a number of competent officers launched a coup... Only to fail to gain Yang support, as the latter was too loyal to the ideals of democracy to support them, leading to a short and disastrous civil war right when the Galactic Empire was undergoing its own civil war (and in fact Reinhardt orchestrated the Alliance Civil War specifically to make sure they wouldn't be a threat or capable of rebuilding after their recent losses). Yang being Yang, he won, restored the democratic but corrupt government... And was the victim of an illegal inquiry because he had saved them in addition to being a war hero, and thus had enough popular support he could have toppled the government by announcing he was doing that. With the Empire fragmented by its own infighting the Alliance could survive, but once Reinhardt stopped the infighting and installed himself as emperor the war ended in short order.
- By volume 4 of Maiden Rose, Eurote and some aristocrats from Taki's country are so determined to get rid of Taki because he's second-in-line to the throne that their in-fighting becomes a great asset to the Western Alliance who they are currently at war with.
- Narrowly averted in Naruto at the beginning of the Fourth Shinobi War. The Kages barely agree to forming an Alliance to counter Obito and their shinobi nearly start fighting one another over old grudges when assembling for battle against a common foe.
- Thanks to an Evil Plan by the villain of the School Festival arc in Negima! Magister Negi Magi, lead Negi was being held responsible for The Unmasqued World, with his True Companions being hunted as accomplices. This had the re-grouped friends fighting far better-trained mage teachers and students employed by the school is guards with Negi taken prisoner. They ultimately succeeded in rescuing the lead, though not without tremendous hinderance and generally having life made a little harder.
- Neon Genesis Evangelion: NERV is fighting to save the world the world from complete destruction, yet the UN keeps cutting its defence budget; heck, it even wanted to Nuke Tokyo 3 into oblivion if the situation looks bleak. Might even be deliberate, seeing as after the Angels are destroyed, civil war swiftly erupts.
- Somewhat justified in the fact that over the course of the series, Tokyo-3 and the evas take an ernomous amount of damage, and NERV's infastructure is incredibly expensive just to begin with (Massive rifles for the Evas to use? Experimental particle beam weapons? That crap's not cheap). It's also implied that the economy of the post-2nd impact world is much worse then ours, particularly if doing your laundry and buying steak dinners is "expensive".
- In Shakugan no Shana, the Flame Hazes tend to be lone wolf types and apparently it's unusual for Flame Hazes to ever work together, even though they have the same goals; Margery Daw is hostile when first encountered (she wanted to kill the one particular Tomogara who isn't harmful). Later, when Wilhelmina shows up, she conflicts with Shana, who has decided to save the world without killing Yuji.
