David Marla Tanner – Mercantile Marine - S.S. Princess Dagmar

Fireman David Marla Tanner – Mercantile Marine, S.S. Princess Dagmar

Early Life and Family Background

Isaac Tanner and Rachel Walters
marriage certificate
Llangennith Parish Church

David Marla Tanner was born in 1900 in Llangennith, the youngest son of Isaac Tanner and Rachel Walters, who married in 1884 at Llangennith Parish Church.

1901 Census

At the time of the 1901 Census, the Tanner family lived at Stimbridge, Reynoldston. Isaac, aged 45, worked as a Woollen Weaver, and Rachel, aged 38, managed the home. Their children were William J. (15), employed as a Flour–Mill Hand; Walter J. (13), a Card Broom Hand; Mary J. (12), a Woollen Weaver; Tom E. (9); and David M. (1).

1911 Census

By the 1911 Census, the family were still at Stimbridge. Isaac, 55, was still weaving; Rachel was 48. The remaining children at home were Walter John (23), a Stone Mason; Mary Jennett (22); and David Morley (12), who attended school. Also present was a servant, Mary Jane Rees (14).

Service at Sea – Fireman, S.S. Princess Dagmar

As a young man, David Tanner entered the Mercantile Marine and served as a Fireman aboard the S.S. Princess Dagmar, a British merchant vessel operating during the First World War. Firemen worked in the intense heat of the stokehold, feeding coal into the ship’s boilers—one of the hardest and most dangerous jobs at sea. In wartime, those below deck had almost no chance of escape during a torpedo attack.

S.S. Princess Dagmar

The S.S. Princess Dagmar was a merchant steamer engaged in short-sea and coastal trade, carrying cargo essential to Britain’s war economy. Like many vessels of her type, she sailed unarmed or lightly armed, making her particularly vulnerable to German U-boats patrolling the Western Approaches and Irish Sea.

On 7^th May 1918, while travelling through hostile waters, the S.S. Princess Dagmar was torpedoed and sunk by the German submarine U-54, a highly active and dangerous U-boat operating in the region. The ship was lost with members of her crew, including Fireman David Marla Tanner, who was only 18 years old.

German Submarine U-54

U-54 was a Type U 51 ocean-going submarine of the Imperial German Navy, commissioned in 1916. Operating mainly in the North Atlantic and waters west of Britain, she carried torpedoes and a deck gun, enabling her to strike merchant shipping with devastating effectiveness. U-54 was responsible for sinking numerous Allied vessels during her career—including the S.S. Princess Dagmar.

Commemoration

S.S. Princess Dagmar
Tower Hill Memorial, London
credit - Benjidog Historical Research Resources:
The Merchant Navy Memorial 

S.S. Princess Dagmar
Tower Hill Memorial, London
credit - Benjidog Historical Research Resources:
The Merchant Navy Memorial 

With no known grave but the sea, David Marla Tanner is commemorated on the Tower Hill Memorial in London, which honours merchant seafarers lost in both World Wars whose bodies were never recovered.

Legacy

David Tanner is remembered as the sole recorded Mercantile Marine fatality from Gower during the First World War. His loss highlights the profound sacrifices made by young men of coastal and rural communities, many of whom went to sea to support their families and found themselves facing the deadly reality of submarine warfare. His name endures as part of the wider story of the Mercantile Marine, whose members kept Britain supplied at immense personal risk.