So I was playing the other day and a situation came up where we didn’t know the rules. I was playing Germany and I had a sub, a battleship and a transport off the coast of France (the sea zone that starts with 1 German sub), and my ships were attacked by US planes. They only got 1 hit on the first attack, so I chose to lose the transport. There were no ships in the Eastern Canada sea zone, although there were a bunch of allied ships at the England sea zone. I wanted to retreat the sub to the Eastern Canada sea zone.
My question is, can I move it there even though the US player was going to move transports there in his non-combat phase? The sub would have retreated just in the combat phase before.