In each of the various short wars I find my IJN in the submarine policy always starts in the "Prize rules" middle ground.*
It occurred to me it should be easy to add to the "doctrine" tab are submarine policy for the start of war.
It also ought to possible to add a single data integer to record between wars what the last submarine policy was and use that at the start of the next war.
It is more likely players will have their sub numbers and research set to one of those and most likely want the same again. They can still change the submarine policy with the existing setting.
>>> * = In accordance with my research levels, death rates of subs and my use of Aviation raiders I prefer to use "fleet support". This does mean they dont see many merchants but thats fine as my AVR tend to out pace the enemy on raiding. I do like having subs appear on the tactical map, provide reports and sometimes snipe an enemy ship. I also like to role play coastal subs as doing numerous inshore chores like mapping for an invasion, inserting or resupplying agents, coast watching for strategic information and so on.