"M" Class Submarine (1917)

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Three of four projected "M" class submarine monitors were completed for the Royal Navy.

Only M 1 saw war service.

Overview of 4 vessels
Citations for this data available on individual ship pages
Name Builder Laid Down Launched Completed Fate
M 1 Vickers 9 Jul, 1917 Collision 12 Nov, 1925
M 2 Vickers 19 Oct, 1918 Foundered 26 Jan, 1932
M 3 Armstrong, Whitworth & Company 19 Oct, 1918 Sold Feb, 1932
M 4 Armstrong, Whitworth & Company 20 Jul, 1919 Cancelled 1918



  • one 12-in 40 cal Mark IX, 50 shells

The 12-in gun could train 15 degrees to either side, elevate 20 degrees or depress 5 degrees.

It proved remarkably workable, and even after the war the British were considering how this might be preferable as an anti-submarine weapon to firing a spread of torpedoes. The submarine was able to transition from periscope depth to firing depth in 25 seconds, and to return to periscope depth after firing in 15 seconds.[1]


M 1, M 2:

  • four 18-in tubes forward, eight torpedoes

M 3:

  • four 21-in tubes forward, eight torpedoes

See Also


  1. The Technical History and Index, Vol. 3, Part 21. p. 8.


"M" Class Submarine
  M 1 M 2 M 3 M 4  
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