A Baltic force of submarines, corvettes, and mines

Which warships are most effective in the Baltic?

Submarines plus adaptable corvette or sloop-sized ships, with minelaying and minesweeping capacity, best fit the Baltic problem.

The historical sloop is a useful conceptual ancestor: a hull that can be adapted among fighting, minelaying, and minesweeping roles. That flexibility fits a constrained maritime theatre where mines and short-range operations matter greatly. It also explains why class labels matter less than mission adaptability.