I find it interesting that in the first two movies the war between the Empire and the Alliance appears to involve only humans, while any alien races that are seen appear to be for the most part neutral, disinterested in the war, and still going about their normal lives. Chewbacca of course is an exception, but apart from him, it seems like George Lucas wanted this to be a war between humans. But this all changed in Return of the Jedi. After two movies, Lucas decided to add some aliens to the Alliance. Not many, but enough to show that some aliens did participate in the war. I know that all the other Star Wars media that came after the original trilogy tells us that alien races were heavily involved in the war, but disregarding all that for now, it certainly seems like Lucas' original idea was for the war to be confined to humans. Why did he decide to modify this plan for Return of the Jedi? I wonder if it was because the alien costumes and effects had improved enough by the time ROTJ was being made, that now he was feeling more confident about giving aliens like Ackbar a more prominent role? Maybe he thought he had made a mistake keeping aliens out of the war in the first place? In Lucas' plans for Star Wars, do we know if the Empire even had any interest in aliens, or did they just leave them alone?