He saw the planes. He knew the risk. It’s not like you were hiding anything or doing anything sneaky. If he was 100% sure what the pieces were he should have doubled checked before calling done to his turn. No do overs. I normally don’t allow do overs on phases of a turn let alone whole turn. Once you say That’s all the combat moves no going back during Non-com and finding a combat you missed.
Question on attacking forces
I am sure this has been stated but cannot find it. Can an axis minor, say Finland for example, attack the same territory as Germany on the same round? Not with the intention of using any combined arms advantages, just simply Finland attacks, softens the opponent and then Germany mops up, or vice versa.
The finnish pieces move as if they are Germans.
All attacks are combined at the same time. Like FEC/ANZAC or Japanese/Siam.