Okay, so there was the pwny war and pwny split, the Trattorian-Bavarian War, the second battle of New York, the creation of Evangelions, the death of Siri and the crusade against Bavaria.
The Pwny war really started with Bavaria allying itself with the pwnies, which can be seen here.
The reason for this was because Piltogg had announced his support for the pwnies, and Kaiser Klaus wanted to become the pwny's main ally to secure more power in the Third Alliance. The Trattorian Empire was then disgusted, as was the RIN. This created a civil war, which involved a lot of posturing and threatening, but the Trattorian Empire nuked the pwny capital.
The Space Mafia then began mining pwnies for rainbow transparent and then selling it to Trattorians
. The effects of this drug were devastating
The Trattorian-Bavarian war was fought because of the pwny war I think. Bavaria's first move was to annex the Silvarian Empire, force a peace with the Britannian League and capture a lot of ships. The war was indecisive, with not much territory gained/lost for either side. Bavaria did acquire a powerful artifakt called the shovel though. An uneasy peace was formed between the two nations.
The Second battle of New York allowed the USA, Praetorians and Scythians to recapture the planet from the Third Alliance. Many other nations fought in the battle, and the Angel Sahaquiel was summoned.
After Siri was killed, the Trattorian Empire left the Third Alliance and joined a coalition against Bavaria. The USA joined the coalition to assassinate Klaus Jr. for war crimes including infecting a planet with an angel, the Praetorians joined because a planet and many ships were infected with an angel, the Space Nazis joined because they're dumb, and the Scythians joined because they had been attacked by Bavaria and they lost a planet to an angel. To secure more power, Kaiser Klaus married off Prinz Karl to Venice. Klaus Jr. was killed by several mercenaries at the wedding.