Just a tip, I used to practice it offline.
Pick up a IL2, blow the town flat........and then shuttle them in.
Put downtime to max to make sure that the downed buildings stay down long enough to get there with the grunts.
PROBLEM: There is now a bug I think, when u do a offline capture, as soon as the tenth grunt gets to the map room, the field is returned to its original country, and all the town and ack is regenerated. Those damn acks shoot you up pretty quick.....