veritas said:

I have to disagree on that one. The Rebel fleet on started to win after Palpatine was killed. Palpatine was probably holding the Imperial fleet together with some kind of battle meditation. Once that was gone the Rebel fleet was able to gain the upper hand.

Timothy Zahn said the same thing in his Heir to the Empire trilogy. I disagree with this. Palpatine's death has little to do with Han blowing up the shield generator on Endor, which is where the battle really turned.