I know that after the battle ends at a non-first planet the warlord goes back to HQ and surviving units remain at planet. However, I was playing someone and he retreated his units after battle, not keeping them at planet. I felt like this was wrong, that the units should remain, but I felt like I couldn't refute his interpretation of the rules. I couldn't find anything in either book that specifically said this was illegal.
I found the part in How to Play that says they remain at planet but he also pointed out the rule about retreating any and all units after combat.
Which of us is right here, and where can I reference the correct answer?
Thanks!