In the face of Britain's powerful war fleet, the Germans decided to bring a new weapon into action: the submarine. Especially once the German army declared unrestricted submarine warfare on 1 February 1917, submarines started playing an important part. From a military point of view, the weapon was a success, with German submarines sinking almost 5000 enemy vessels during the war.

'Underwater claustrophobia' tells you more about the daily life on these submarines.