If I do an amphibious assault and I have carriers (filled with planes) and a cruiser and I move 3 spaces (navel base) to get to my land target but in the way I have to clear out a German sub(s) can the planes be used in the land assault? I do no have the rulebook handy, but how do amphibious assaults work?
Again, subs alone do not stop movement and they do not stop amphibious assaults (unless you CHOOSE to fight them). You can either choose to combat the sub in the seazone that you’re assaulting from OR you can choose to ignore the sub. If the sub is between you and your desired seazone, you can attack the sub with some units AND move transports through with other units - they NEVER stop units from moving over them.
If you choose to engage the sub in a seazone you will amphibiously assault from, you cannot roll for shore bombard. Additionally, if you engage the sub with ANY collection of units that doesn’t include a destroyer, the enemy sub can choose to submerge before ANY combat rolls, thereby disengaging from combat before any shots are fired.
Amphibious assaults work as follows:
Combat move to the seazone. If there are enemy SURFACE warships and/or scrambled aircraft, you must engage them in a naval battle (and defeat them) in order to land your units on shore. If there are only transports and sub and no scrambled aircraft, you can choose to ignore the transports and subs and amphibiously assault units with battleships and cruisers assisting in one round of shore bombardment. If you choose not to ignore them, you’re engaged in a naval battle (and no halfsies on some battleships bombarding and others fighting in the naval battle - it’s all or none).
If there is a naval battle, you cannot shore bombard. If you cannot defeat the enemy naval/air units once engaged, you must either retreat to a friendly seazone (no enemy surface warships) or you will lose your transports. Only once all enemy combatants are removed do your transports unload. At this point, you naval units cannot retreat from the seazone.
Units from transports CANNOT EVER retreat once they are offloaded - they fight to the death. Aircraft or land units attacking from other territories can choose to retreat after the first round of combat. If your naval units could not clear the seazone and were forced to retreat, all land and air units that were tasked to the combat but weren’t on transports are still required to fight at least one round of combat before they also can retreat.
These are OOB and Alpha rules. They haven’t changed since AA50 (with the exception of scrambling).