I was just watching clone wars and realized that anakin was a commander in the clone wars. Wasn't Luke a Commander in ESB? Apparently the Skywalkers are only able to advance so far in their respective militaries. Just a thought.

I think he became a General by ROTJ. Same with Anakin, if I remember correctly they referred to him as 'General' in the CW cartoons.

Funny enough, Han, Leia and Luke were all generals by then. Three generals on one mission, it´s insane!

I don't want to pull in the EU, because I know what people feel about it here, but from what I've read any Jedi Knight or Master was automatically a General of the Army of the Republic and a Padawan was automatically a Commander.