HMHS Rewa, a fully lit hospital ship, was proceeding up the Bristol Channel on January 4, 1918 returning 279 wounded from the Mediterranean when at 23:15 a torpedo fired from an unseen submarine struck the port side of the ship. The unseen U-boat, SMS U-55 under the command of Oberleutnant zur See Wilhelm Werner, apparently fired only one torpedo and did not molest the ship further while it was being abandoned. This was unlike the Belgian Prince, which was sunk in July of the previous year where Werner had deliberately drowned the crew by submerging his submarine with the men on the casing.

Twenty minuets after she was hit, Rewa slipped under the waves taking four crewmen with her, which was a small miracle considering that over 560 people, including the wounded, were on the ship. The skill and leadership of Captain J. E. Drake kept the orderly evacuation possible and 14 lifeboats were launched. All the survivors were picked up at 03:00 the next morning.