M Class (1918) SS

The M Class submarines were designed as Monitors to act as raiders against enemy merchant shipping. They were armed with 12in guns salvaged from the Battleship HMS Formidable

In action it was intended that when fired the gun muzzle would be above the water with the main body of the submarine still 12-20 feet below water. A bead sight on the gun muzzle allowed the gun to be sighted through a periscope. Their use was very limited as the gun had no turntable and the boat had to surface to reload.  

The Washington Treaty of 1922 limited submarine guns to a maximum of 8in. So M2 was converted to be an aircraft carrier, and M3 converted to a minelayer. While M1 was sunk before her gun could be removed.

An interesting experiment took place in 1924 when each M Class submarine was repainted to test hull colours as seen from aircraft. M1 was repainted grey-green, M2 dark grey and M3 dark blue.

(NB Transfer to M1 file when done.

Loss of M1 was caused by glancing collision with the SS Vidar  which struck the forward upper casing of the gun housing. Causing the gun to be dislodged, and the gun casing to partially detach. The pressure hull was breached and the forward part of the hull filled with water. It is believed that some crew in the rear of the ship survived for a time but finally equalised pressure to their intact compartment, opened a hatch and tried to reach the surface. No bodies were ever found. )


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This page last edited - 05 March, 2013.

Copyright Ian M King, except where otherwise indicated.