 Financed , trained and equipped by the Germans , the saboteurs sank the armed trawler HMT Erin , and destroyed the auxiliary minesweeper HMT <unk> , which resulted in the deaths of six British seamen on 18 January 1942 . Plazas was assisted by the Spanish naval commander of Puente Mayorga , Manuel Romero Hume , who allowed him to beach a rowboat there . The British intelligence was able however to counteract the sabotage operations . In March 1942 , a Gibraltarian , José Key , one of the most prominent agents working for the Germans , responsible for the collection of information on military movements for the Abwehr was arrested and executed in Wandsworth Prison in late 1942 . By September 1942 , Plazas , whose activities were closely monitored by the British at that time , resigned and left Carlos Calvo , his second in command , in charge of the operations . In late 1942 , the German headquarters in Berlin ordered the sabotage operations being expanded . In early 1943 , the arrival of an experienced head of Abwehr operations in Spain improved the outreach of the operations . 
