During World War II, Operation Lost was a reactive seven-man Special Air Service operation inserted into Brittany alongside Operation Dingson on 22–23 June 1944. The team, drawn from officers and men of 37 Military Mission and the SAS Brigade, was originally inserted to discover what had happened to the Dingson base after it had been attacked and dispersed by German led rear area security troops. These SAS operations trained and armed local fighters and harassed the defenders as they tried to react to the Overlord landings. The Lost team was active from 23 June to 18 July.