Multinational Forces: Transports belonging to a friendly power can load and offload your land units. This is a three-step process:
1. You load your land units aboard the friendly transport on your turn.
2. The transport’s controller moves it (or not) on that player’s turn.
3. You offload your land units on your next turn.
Unloading in an enemy territory occurs in your scenario in US’ combat move phase, followed by the battle.
Unloading in a friendly territory occurs in US’ NCM phase.
I love buying subs as germany. I think its the best cost efficient way to slow down US and put a stranglehold on UK economy. Having a lot of subs and weakening UKs economy will make the UK think twice about buying naval units. I find that attacking USSR on G2 has worked best for me. I will also buy at least 3 subs per turn and have at least 12 subs in the atlantic by the time the US comes over. The US cannot be stopped only delayed a round or two which will be huge.