The republic and the Jedi went to war with the Seperatists, a large group of star systems in the galaxy who wanted to leave the republic. But why were they really evil? The Republic was corrupt, George Lucas said that himself and the movies said it too, that's why they left it. How was the Galactic Republic the ideal government in the galaxy if they started a war over people who wanted to leave them, for being a corrupt bad form of galactic government in the first place? They were not trying to harm the Republic.