In 1943, the middle of World War II, No. 4 British Commando were involved in a mock seaborne raid codenamed "Exercise Brandyball", which took place on the 300-foot (90 m) cliffs, near Bosigran, known as the 'Brandys'. The training exercise was deemed one of the most hazardous and challenging of the war, beginning with a seaborne landing, followed by a climb up the vertical cliffs with full kit to destroy the target, an old disused tin mine. On the rehearsal day of 6 June, the weather was not good and one of the boats sank with the loss of two commandos. These events were filmed by Allied officers, as observers from all the services were present, including General Bernard Montgomery. The archives are now held in the Imperial War Museum. The following day the men decided the operation should continue, and it was successfully completed on 7 June.