He did fight for it, just not in the way that you would think. The people that passed away before Jesus had died could not get to Heaven, as the gates of it were closed from Adam and Eve being kicked out. When Jesus died, the gates were open and he descended into hell, where all of the prophets and good people were, so that He could bring them into Heaven. It was a sneak attack because the devil did not expect what Jesus was going to do.