Hints for Axis sub warfare:
- A good sub is a living sub. Do not overdo, do not use the Subs too early (wait until France falls), wait until you have numbers, TECH and use them in packs. Do not use them on the "water highways" near Britain unless you really have a stronger navy than the Allies have (quite unlikley but sometimes possible if they sent alot of navy to the Mediterranean). The golden age of Subs is probably in 1941-1943 so make sure you have not been doing prematurely fruitless attempts spoiling this opportunity.
- Use the Sub in combination with other threats because UK has a limited budget. After France surrender, pressuring UK by using air duels and bombing UK cities (will cost UK alot intercepting) combined with Italian naval action in the Mediterranean (might divert some UK navy there to help out near Egypt) and combined with a pack of 4-5 Axis subs showing up in some far west location attacking convoy means UK cannot afford doing all at once.
- Do not think you can fight the whole royal navy instead hit & move. Try to find a new place to hit again some turns later. Count UK Destroyers, if you see they have built destroyers then you know you need to be more cautious and await more tech and new subs to be strong enough. Often UK cannot afford building destroyers, investing in tech, replacing air casualties over Britain an help out Egypt at the same time so just be smart and do not overdo or kill yourself because if you mess up it will take the pressure off the UK
- There are 3 convoy routes and protecting them all means Allies need to use 1/3 of its navy while Axis can focus them all in one big pack. Use this to your advantage but do not stand too close to the large ant hill (=UK) because standing in the middle of the trail you will be attacked
- Use the Sub invisibility feature to your advantage. Remember as soon as you attack you become spottable to the enemy. Sometimes a large sub pack can even neglect attacking with all Subs just to leave some of them covering and doing a suprise attack on the first incoming ships that try to attack your newly spotted Subs. The turn after your attacks on convoys you can just move again and become invisible.




