I think this is a good idea. Beacause in real war it was generally the defender that retreated. Not the attacker. (Most of the time)
I definatly agree on this. Of course both attacker and defender must be able to retreat. And since a turn is 6 months, the out-of-box rule is even weirder. I guess its a carryover from Risk. That figures. Larry played too much Risk when he was a teen, and borrowed some bad impressions from that retarded and very, very lame game.
So the rules should say, that after first round of combat, the attacker may retreat, or the defender may retreat, or the battle may continue. Easy as that. Of course the defender must retreat to a territory that is friendly, just like a plane after combat must land in a friendly space. If this territory was attacked, but remained friendly, then the defender may retreat there, as long as the combat is resolved. But the defender may not retreat to a friendly territory that are going to be attacked.
Its two ways to solve this issue. The attacker choose the orders of attacks, and may of course attack the defender’s potential redraw areas, just to denie any retreats. This is a common strategy in real world too. To let the defender choose the orders of attacks, just to denie this strategy, is insane and pure bedlam.
The other solution is to use the rule that keep aircrafts in air until all battles are resolved, and then land them in the proper spaces. Then the defender could stop a combat, and make the retreat-move after all combats was resolved.