To provide medium and light fire support to land units close to the coastlines, the Royal Navy constructed a class of 14 small monitors fitted with reserve guns for obsolete armoured cruisers. Four of these are in service close to home, three of which are armed with 7.5" guns, while one (M27) has only a 6" gun.

Ship data

Relative combat value: 257 (116 with M27)

Basic damage control capacity: 102%


Displacement: 540 tons

Length: 54 m

Width: 9 m

Draught: 2 m

Standard crew: 69


Maximum speed (undamaged): 11 knots

Endurance: 3706 km

Coal capacity: 100 tons

Armour protection

Conning tower armour: 0

Hull armour: 0

Main belt armour: 0

Deck armour: 0

Best armour type: none


1 x 7.5 inch BL Mk III, centrally controlled. Ammo: 150 rounds (M27: 1 x 6in BL Mk VII (L), centrally controlled. Ammo: 150 rounds)

1 x 12-pdr 18cwt QF Mk I, centraaly controlled. Ammo: 200 rounds

1 x 6-pdr 8cwt QF Mk I, locally controlled. Ammo: 200 rounds

Ships in class

  • M15 (away in foreign waters)
  • M16 (away in foreign waters)
  • M17 (away in foreign waters)
  • M18 (away in foreign waters)
  • M19 (away in foreign waters)
  • M20 (away in foreign waters)
  • M21 (away in foreign waters)
  • M22 (away in foreign waters)
  • M23 (away at the Mediterranean)
  • M24
  • M25
  • M26
  • M27
  • M28 (away in foreign waters)