M15 through M28 formed a 14-ship class, each armed with one 9.2-inch gun, a 12-pounder, and a six-pounder. M15 was sunk by UC-38 on 11 November 1917. Four ships were lost in or as a consequence of the First World War, including two scuttled while supporting White Russian forces to prevent capture by the Communists. Other hulls had long careers as minelayers or drill ships, with M23 surviving until 1959. The class used triple-expansion, paraffin, and semi-diesel machinery across different members. That variation shows how much propulsion experimentation remained inside an otherwise standardized wartime design.
Notable Point · 26:14-29:03
M15 class: mass-produced small monitors
Fourteen M15-class monitors demonstrate wartime standardization, but their varied propulsion arrangements show the compromises behind rapid construction.