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Royal Marines WW2 DEMs Gunners

Updated: Oct 7, 2023

Following the valuable lessons of Defensively Armed Merchant Ships (DAMS) in the First World War, in 1919 the Cabinet approved an Admiralty and Board of Trade policy for the strengthening of merchant vessels during construction, in order to allow the rapid fitting of armaments when necessary. However, later that year the obligation to do this was withdrawn due to opposition from ship­owners on cost grounds. Between 1922 and 1937 only two vessels had been ‘stiffened’ to prepare for the fitting of guns.

In 1937 the Admiralty and the Board of Trade formed the Shipping Defence Advisory Committee and by the end of 1938 the Admiralty and Treasury had come to an agreement regarding costs. Finally, preparations were underway. The strengthening of ships in readiness for the fitting of guns began and some training of Merchant Navy officers started, the first gunnery training course taking place on 18th July 1938. In June 1939 the Admiralty Trade Division established the Defensively Equipped Merchant Ship (DEMS) organisation.

A merchant vessel being retro fitted with a quick firing gun.

In the first 6 months of the Second World War some 1,900 ships had been defensively equipped and by the end of 1940, 3,400 of the intended 5,500. [1]

Old naval guns had been stored since 1918 in ports for possible use. In the Second World War the objective was to equip each ship with a low-angle gun mounted aft as defence against surfaced submarines and a high-angle gun and rifle-calibre machine guns for defence against air attack. 3,400 ships had been armed by the end of 1940; and all ships were armed by 1943

A double decker bus serving as a mobile DEMS gunner’s training classroom.

The low-angle guns were typically in the 3-inch to 6-inch range (75–150 mm) depending on the size of the ship. Rifle-calibre machine guns were augmented or replaced by Oerlikon 20 mm cannon as they became available. The high-angle QF 12pdr Mk V mount was the most common anti-aircraft gun and later ships sometimes received Bofors 40 mm guns.

A Royal Marine training Merchant seamen in gunnery on the top deck of a double-decker bus converted into a mobile class room.

Untrained gunners posed significant risk to friendly aircraft in the absence of efficient communications. DEMS guns were manned by 24,000 Royal Navy personnel and Royal Marines and 14,000 men of the Royal Artillery Maritime Regiment. 150,000 merchant sailors were trained to assist by passing ammunition, loading and replacing casualties. Initially, Royal Artillery personnel provided anti-aircraft protection by bringing their own machine-guns aboard ships operating close to the British Isles.

MV SS Abosso torpedoed by U.575 29th October 1942 in mid-Atlantic. Sergeant Dobson RM serving as a DEMS gunner killed. (

DEMS gunners were often retired military personnel and young Hostilities Only ratings, commanded by a petty officer or Royal Marine sergeant. Large ships sometimes embarked a junior naval officer to command the DEMS gunners. [2]

All members of the armed forces that served on board a DEMS ship were required to sign on as members of the crew, i.e. as merchant seamen and were therefore under the authority of the ship’s master. As merchant seamen, military personnel could visit neutral countries without being interned. [1]

HMS Glendower in North Wales and HMS Wellesley at Liverpool were just two of several DEMS training establishments preparing sailors destined for war service in merchant ships. By 1944, some 33,000 DEMS gunners had been trained at Glendower and Wellesley alone.

The training comprised five weeks’ basic naval training. This prepared them for two-and-a-half weeks of gunnery and two-and-a-half weeks of advanced seamanship instruction. The final part would be their specialised DEMS training. This lasted three weeks but was increased to four to cover the whole variety of weapons which could be fitted to merchant vessels. Army personnel were also drafted to augment Royal Navy DEMS gunners on board merchant ships.

The drafting of Army personnel on board merchant vessels allowed more Royal Navy servicemen to be released for service in the operational fleet. [3]

A Colour Sergeant instructor of the Royal Marines instructing men of the Merchant Service in how to load the "Pillar Box". (note the poppies in their caps)) © IWM A 20390

Royal Marine ranks employed as DEMS gunners were designated as Acting Gunlayers.

On 15 July 1943, AFO 3210/43, described the Quarters Rating 2nd Class and 3rd Class badges were to be incorporated with the letters D.E.M.S. (Defensively Equipped Merchant Ships) for wear by D.E.M.S. rating qualified as Acting Gunlayers and Acting Semen gunners respectively. The Acting Gunlayer D.E.M.S. badges was Crossed guns with star above with letter Q and latter DEMS below, and the Acting Seaman Gunner D.E.M.S Single Gun with star above and letter Q and letters DEMS below. Both badges were issues in Red and blue, AFO 5523/43, 18/11/1943. [4]

HMS President III was an administrative unit for the Defensive Equipped Merchant Ships (DEMS). It was located at Dedworth Manor in Windsor between 1940 and 1945.

85 Royal Marines DEMS gunners are listed on the Royal Marines Roll of Honour & War Graves Database open here and search HMS President III in Unit/ Formation:


Service: Royal Marines

Unit/ Formation: H.M.S. President III

Regiment: DEMS Gunner Whale Factory Ship Sourabaya

Rank: Sergeant

Service Number: PLY/15676'

Location: United Kingdom

Period/ Conflict: World War II

Age: 48

Date of Death: 27/10/1942


Details of Service: Percy was a DEMS gunner on board British whale factory ship Sourabaya when hit on 27 Oct 1942. When Sourabaya was torpedoed by U-436 on October 27th, 77 of her crew of 158 were lost.

British whale factory ship Sourabaya

The master, 36 crew, 24 passengers, 16 DBS and four gunners were picked up by HMCS Alberni (K 103) (Lt I.H. Bell, RCNVR) and HMCS Ville de Quebec (K 242) (LtCdr A.R.E. Coleman, RCNR) and landed at Liverpool on 2 November. 26 crew members, 31 passengers, 16 DBS and four gunners were picked up by the Bic Island, which was torpedoed and sunk with all hands by U-224 (Kosbadt) on 29 October.

BL 4 inch Mk VII low-angle gun on a DEMS in 1943, an obsolete WWI gun typical of WWII DEMS armament (Wikipedia)

The British landing craft HMS LCT-2281 (291 tons) on deck was lost with the vessel.

Family Information: Son of Arthur and Alice Adwick; husband of Elizabeth Ann Adwick, of Rawmarsh, Yorkshire.

Other links:

[1] Archives Centre, Maritime Museum - Defensively Equipped Merchant Ships (DEMS)

[3] The Merchant Gunners - Written & Researched by David J.B. Smith

[4] Navy Gunnery Badges worn by Royal Marines - Mark Philips - Royal Marines Historical Society

[5] Details of sinking: Wreck Site

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1 Comment

My father in law was a DEMS gunner. Stanley Victor Brickell b.1920. Died in 1974 but although we have his medals and limited info, we don’t know which ships he served on other than HMS Devonshire and SS Bactria. He was sunk several times - ( not those ships as think they survived the war) once in Atlantic and once in Indian Ocean. Royal Navy but seconded to Merchant Navy.Trained at Pwellili HMS Glendower. Can’t find his records - where might they be ? Any help gratefully received !

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