Ahh. so in naval battles with air and subs, air units must be rolled seperately from naval units? This isnt in the rules either, but a logical conclusion from this thread. How else so you know what are air unit hits or not. On the converse, a DD present allows air to hit subs, but not vice versa. So if a DD is present, then subs must now roll seperately from other naval units. Well, i guess they are the only unit that defends at 1, so this is a mute point on defense, but on offense, it an annoyance. This is complicated!!
-) if no DD is present, subs anyway hit during surprise strike, so then you roll for them seperately anyway.
-) if a DD is present, you just need to remember how many hits you had with subs. as the amount of sub hits equals the amount of naval units you have to pick as casualties.
-) if there are air units, but NO DD, you have to roll air units seperately, so you know how many surface warships are subject to be removed from the game.