A cheap threat that demands an expensive response

A minefield does not need a large fleet behind it to complicate operations; it needs a ship able to place it in the right waters. One or two Brummer-class ships could lay hundreds of mines and return home, while the defender could not know where the threat would appear. The response requires patrols, screening forces, and minesweepers, all of which consume scarce ships and crews. This imbalance made mines strategically valuable despite the greater prestige attached to battleships and submarines.