On the morning of 9 November 1918, under the command of Captain Francis Wade Caulfeild, "Britannia" was on a voyage in the western entrance to the Strait of Gibraltar when she was torpedoed off Cape Trafalgar by the German submarine "UB-50". After the first explosion, the ship listed ten degrees to port. A few minutes later, a second explosion started a fire in a 9.2-inch magazine, which in turn caused a cordite explosion in the magazine. Darkness below decks made it virtually impossible to find the flooding valves for the magazines, and those the crew did find were poorly located and therefore hard to turn, and the resulting failure to properly flood the burning magazine probably doomed the ship. "Britannia" held her 10-degree list for 2 and a half hours before sinking, allowing most of the crew to be taken off. Most of the men who were lost were killed by toxic smoke from burning cordite; 50 men died and 80 were injured. In total, 39 officers and 673 men were saved.