Page 20 in the Europe rulebook says its possible:
“An attacking land unit can assault a coastal territory from an ally’s transport, but only on the attacking land unit owner’s turn.”
Clear enough! Thank you!
The transport unit description doesn’t seem to contradict this.
I still am a bit confused because of the Transport unit description
“Amphibious Assaults: A transport can take part in an amphibious assault step of the Conduct Combat phase. That is the only time a transport can offload into a hostile territory.”
So in fact a transport can offload into a hostile territory under two circumstances:
1. own troops in an amphibious assault on it’s own combat move
2. allied troops (cargo) as part of the combat move of the allied nation
(but here the Transport cannot be part of the amphibious assault because allied nations never attack together)
But no more arguing, I am convinced now.
Thank you again.