German submarines target merchant ships

The Wilson line ship the SS Eskimo. Gouache study for a poster. © Hull Museums.

In February 1915 German U-boats (submarines) began to deliberately target merchant ships supplying Britain with essential food and military supplies. Germany declared the seas around the British Isles a war zone and warned that the German navy would attack all merchant ships, including those owned by neutral countries.

A merchant ship is a vessel that transports cargo, passengers or both. In order to win the war it was vital that the Allies were able to move troops, food and equipment by sea. The supply of food to the civilian population, as well as equipment and ammunition, was dependent on imports from Europe and across the Atlantic. U-boats fired torpedoes at ships and also laid mines in the water in busy shipping lanes in the hope that ships would run into them.

Germany changed its policy in May 1916 due to pressure from the USA and promised to stop the indiscriminate sinking of non-military ships. However, it took up unrestricted submarine warfare again in 1917 which was one of the factors that prompted the USA to join the war.

The Wilson line, based in Hull, was the biggest privately owned shipping company in the world. Hull was the third largest port in the UK in 1914. The First World War had a severe impact on the merchant shipping industries that operated out of Hull, Goole and Grimsby. The Wilson line lost 43 steamers, about 50% of its effective pre-war capacity, and over 800 Hull merchant seamen lost their lives through enemy action during the four years of the war.

Learning resources

For downloadable images, teachers’ notes and activity ideas relating to the war at sea and its impact on the Humber region, go to