In March 1915 Great Britain ordered the construction of 19 small monitors, under the Emergency War Program. Like their larger relatives – already under construction - they were designed to make use of artillery pieces scavenged from spares or taken “second hand” from decommissioning cruisers. They were very simple ships and built to commercial standards. Propulsion was provided by whatever plant was available. This resulted in a very diverse group of ships, divided into two classes...
HMS M.17 – mounted a BL 9.2” Mk.X gun, taken from spares (for Drake- and Cressy-class cruisers). Secondary armament was provided by a QF 12pdr Mk.I Naval Gun and a QF 6pdr Mk.I Hotchkiss. She was powered by a 800 ihp, triple expansion steam plant. HMS M.15 and HMS M.16 where built to the same specifications.