In 1942, Diego-Suárez was the primary objective of Operation Ironclad, the starting point of the Allied invasion and capture of Madagascar. The Allies were concerned that Japan would pressure Vichy France into granting use of Madagascar, as they had with French Indo-China during the previous year, and determined that the island should not be made a base for the interception of Allied shipping. Diego-Suarez, with its superb harbour and a concentration of government officials, was selected as the initial invasion point. The Japanese responded with an attack by midget submarines on the British naval forces in the harbour, damaging the battleship and sinking the oil tanker "British Loyalty".