M Class

Lord Fisher submitted a proposal to the First Lord, Lord Balfour, in August of 1915 to mount a 60 ton 12 inch gun from a battleship of the Majestic class. The gun was to be situated in front of the conning tower.

The idea was then to search for a target at periscope depth of 30 feet. Once the target was in sight the submarine was to be lined up with the target with the gun elevated at the appropriate angle. With about 6 feet of the gun barrel above the surface, the gun would be fired and the submarine would return to a safe depth.
The idea was eventually approved with orders for four, two at Vickers and two with Armstrong Whitworth using the keels of (See Footnote) K18, K19, K20 and K21. A surface speed of 15 knots was achieved during trials using two Vickers designed 12 cylinder diesels. Submerged they were driven by four double armature motors able to reach a speed of 9 knots.

The boats were reported as being very stable when handling and were able to dive in 30 seconds. The gun proved reliable, even after being underwater for several hours. The firing and submerging operation took 55 seconds. These boats had a diving depth of 200 feet.

The first orders were placed for the first of the class in February 1916 but it was not until April 1918 that M1 was ready.

After the Washington Disarmament Treaty of 1920 which stated that no submarine could have a gun larger than an 8 inch, M2 and M3 had their guns removed.

M2 was refitted with a seaplane hangar replacing the gun and a catapult to launch a small Parnall Peto seaplane.

M3 was converted to an experimental minelayer in 1927, with 100 mines on rails inside a free-flooding casing outside the hull. The mines were laid over the stern by means of a conveyor belt. This method proved to be more than efficient.

These boats (as K's) were originally armed with four 18 inch bow tubes but M3 had these replaced with four 21 inch.

3 Built

Submarine	Builder	Built
M1 and M2	Vickers, Barrow-in-Furness	1918 - 1919
M3 and M4	Armstrong Whitworth, Newcastle-on-Tyne	1920

M4 was cancelled. Work was suspended at the time of the Armistice, and cancelled shortly afterwards on 26th November 1918. She was launched in July 1919 only to clear the slipway and she was sold to the builders for scrap.

Technical Information

Displacement (tons):	1,610 sf 1,950 sm
Length (ft):	295.9oa
Breadth (ft)	24.7
Draught/Height (ft):	Not known at present.
Machinery:	2 x 12 cylinder Vickers Diesel engines 1,200 bhp each. 4 double armature motors 400 bhp each. Twin Screws
Speed (kts):	15 kts sf 9 kts sm
Oil Supply (tons):	na
Armament:	1 x 12 inch gun, 1 x 3 inch gun. 4 x 21 inch tubes or 4 x 18 inch tubes.
Range:	2,500 miles at 16 kts or 4,500 miles at an economical cruising speed sf. 10 miles at 10 kts sm.
Complement:	65 officers and ratings.

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H.M. Submarine M1

Type:	M Class
Pennant No.:	M.1
Laid Down:	July 1916.	Vickers, Barrow-in-Furness.
Commissioned:	17th April 1918.	Cdr. M. Horton.
Commander:	1918 1921 1925.	Cdr. M. Horton. Cdr. C. G. Brodie. Lt. Cdr. A. M. Carrie.
Complement:	68	6 Officers and 62 Ratings.
Service Career:	1918	11th Flotilla.
Fate:	Served in the Mediterranean under Horton until the Armistice. Sank after a collision with the Swedish collier SS Vidar off Start Point with the loss of all 69 crew, 12th November 1925. The wreckage of M1 was not found until 1990 by the Royal Navy and more recently by divers in 1999.

The following newspaper cuttings were forwarded to me by Matthew McCoy of Plymouth, whose wife's Great Grandad went down with the M1 in 1925.

Apparently they were taken from the Western Morning News and The Evening Herald.

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H.M. Submarine M2

Type:	M Class
Pennant No.:	M.2
Laid Down:	13th July 1916.	Vickers, Barrow-in-Furness.
Commissioned:	14th February 1920.	Not known at present.
Commander:	1932.	Lt. Cdr. J. D. de M. Leathes.
Complement:	68	6 Officers and 62 Ratings.
Service Career:	Not known at present.	Not known at present.
	To conform with the Washington Disarmament Treaty of 1920 the 12 inch gun was removed. She was refitted with a seaplane hangar replacing the gun and a catapult to launch a small Parnall Peto seaplane.
Fate:	Lost during exercises off Portland 26th January 1932. It was believed she had dived with both inner and outer hangar doors open though the cause was never disclosed. Over the years M2 has been dived on by many divers who have reported that she is on an even keel and in such condition that she looks as though she may burst into action at any time. The wreck of M2 is used in the training of sonar operators.

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H.M. Submarine M3

Type:	M Class
Pennant No.:	M.3
Laid Down:	Not known at present.	Armstrong Whitworth, Newcastle-on-Tyne.
Commissioned:	1920.	Not known at present.
Commander:	1923-1925.	Lt. Cdr. C. Mayers.
Complement:	68	6 Officers and 62 Ratings.
Service Career:	Not known at present.	Not known at present.
	To conform with the Washington Disarmament Treaty of 1920 the 12 inch gun was removed. She was refitted as a submarine minelayer capable of carrying more than 100 mines. The method of laying the mines over the stern by the use of a conveyor belt proved more than successful and she suffered no disasters in her career.
Fate:	Scrapped in 1932.

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