Improvised anti-submarine defence in shallow water

Four M15-class ships were lost, including one to a submarine-laid mine and another to a torpedo from a coastal minelayer. Reports suggest that some monitors may have equipped themselves with depth charges after crews saw submarines beneath them in shallow water. The detail shows that these gun platforms were participants in an improvised anti-submarine struggle as well as shore-bombardment vessels. Their operating environment brought monitors, mines, and small submarines into unusually close contact.