Mass submarines as a barrier in home waters

Does the campaign really have a thousand submarines, and how are they deployed?

Yes. They are built in large batches and dispersed so dense local groups make the Caribbean and other home waters costly for enemy fleets to enter.

The player lists roughly a thousand submarines alongside 435 destroyers, 123 light cruisers, 50 cruisers, 23 battlecruisers, and 75 battleships. The submarines are built in batches of hundreds and dispersed across defended regions. Dense local groups turn approaches to the Caribbean and other home territories into dangerous waters for an attacker. A comparison with German ports in 1943 shows how concentration and geography can matter as much as the total number of boats.