Li Shimin led a coup that resulted in the death of his older brother, and for good measure, his younger brother was killed as well. But being next in line to the throne was no longer enough. Shimin forced his father into retirement and declared himself emperor. "I had to kill my older brother because he was the only thing in the way of me and the throne. But then he died my father reconsidered and chose my younger brother because he thought i wasn't worthy enough so I had no choice but to kill him to. And with no one left for my father to choose he chose me and all I had to do was force him into retirement. " This is what Taizong had to say in his defense.