In very difficult circumstances, Obito achieved to invoke juubi. After playing with juubi, alliance and kakashi, things did not go well and he came so close to death. Additionally, Madara tried to take control. I dont think any thing worse than these for obito. However, he left all these behind by beeing juubis jinchuuriki. I just wonder why he did not become jinchuriki in an isolated unknown deserted place instead tried to make many zetsus to kill fodders. The only logic for me can be that he merged all nations in a way like that, but this idea is losing its validity every week. The only thing remaining is that he is another psycho like madara, they search for fun
Does anyone have a better idea for why obito declared war?