When landing troops on more than one enemy world in a turn, only one ground combat actually occurs at start of next turn.

Description

I invade (let's say) 3 worlds this turn. I then end the turn, and the ground combat pops up (after the other players get their turn, of course). I am then placed into ground combat for one of those worlds (I haven't really found a definate pattern as to which world I am dumped to, but typically it's the first one I invaded). At the end of that combat I am placed back into the standard orders screen (the main game screen). I now have 1 world invaded (or lost) and 2 in 'limbo' (pending). If I do not invade any other worlds, at the beginning of the NEXT turn, I am dumped into ground combat on one of the two 'pending' worlds. So, essentially I can invade as many worlds as I want, but it'll take x turns (x=number of worlds I invade) to resolve them.