History
United Kingdom
Name	HMS M20
Builder	Sir Raylton Dixon & Co.
Laid down	1 March 1915
Launched	11 May 1915
Fate	Sold 29 January 1920
General characteristics
Class and type	M15 class monitor
Displacement	540 tons
Length	177 ft 3 in (54.03 m)
Beam	31 ft (9.4 m)
Draught	6 ft 9 in (2.06 m)
Propulsion	4-shaft Bolinder 4-cylinder semi-diesel 640 hp
Speed	11 knots
Complement	69
Armament	As built 1 × BL 9.2-inch Mk VI gun 1 × 12-pdr (76 mm) QF Mk 1 gun 1 × 6-pdr (57 mm) QF MK 1 AA gun 1918 1 × BL 9.2-inch Mk VI gun 1 × QF 3-inch (76.20 mm) AA gun 1 × 6-pdr (57 mm) QF MK 1 AA gun

HMS M20 was a First World War Royal Navy M15-class monitor.

Intended as a shore bombardment vessel, M20's primary armament was a single 9.2 inch Mk VI gun removed from the Edgar-class cruiser HMS Gibraltar.^[1] In addition to her 9.2-inch gun she also possessed one 12 pounder and one six-pound anti-aircraft gun. She was equipped with a four-shaft Bolinder two-cylinder semi-diesel engine with 640 horsepower that allowed a top speed of eleven knots. The monitor's crew consisted of sixty-nine officers and men.

HMS M20 ordered in March, 1915, as part of the War Emergency Programme of ship construction. She was laid down at the Sir Raylton Dixon & Co. Ltd shipyard at Govan in March 1915, launched on 11 May 1915, and completed in July 1915.

M20 served within the Mediterranean from August 1915 to December 1918. She did not return to Home Waters, paying off at Malta.

M20 was sold on 29 January 1920 for mercantile service as an oil tanker and renamed 'Lima'.

• Colledge, J. J.; Warlow, Ben (2006) [1969]. Ships of the Royal Navy: The Complete Record of all Fighting Ships of the Royal Navy (Rev. ed.). London: Chatham Publishing. ISBN 978-1-86176-281-8.
• Dittmar, F. J. & Colledge, J. J., "British Warships 1914–1919", (Ian Allan, London, 1972), ISBN 0-7110-0380-7