I would have liked a rule that allowed subs to patrol a sz all the time (forget about the escort/unescorted stuff). If you enter a sz that has an enemy sub(s), each sub gets to fire one attack shot @ 2 as an option at any surface ship that enters that sz (even if they are just passing through). The battle would only last 1 round. The player moving through would be allowed to fire all his war ships def values in return, if you exercise your sub attack. The enemy moving through gets to pick his casualties as normal w/tpts as the last resort. As I said it should be the option of the player who owns the sub(s) and probably only in the combat move phase of the enemy, so you could choose your moments when it gives you an advantage. They could not ignore you if you chose to attack. Enemy combat move w/destroyer could work as it does now, it only effects if sub casualties fire back, or could simply deny the sub(s) attack all together. I wouldn’t allow the sub to stop movement, only delay it long enough for the 1 round sea battle. After that surviving ships can continue on if they still have movement left. One sub won’t make much of an impact, but 3 could. If it was the discretion of the sub owner, then any tpts moving through alone would get shot at. Same would be for several tpts with only 1 war ship. This would change how subs work slightly, and by using such a rule basically raises their def value to 2. As Germany 3 subs grouped together in one sz are like sitting ducks def at 1’s OOB. This wouldn’t stop lone transports from off loading either, if they survive the 1 round sea battle they can off load. This is just my take on it, and we have used it as a house rule in AA50, but not in G40.