The COPP Depot was set up in 1943 on Hayling Island based at Hayling Island Sailing Club. In preparation for the invasion of Normandy, the British carried out Operation Postage Able, in which a midget submarine took a team close in to the planned landing sites. The team took samples from the beach to determine its ability to bear vehicles, and, together with depth soundings and other observations, large-scale models of the beaches were constructed to aid planning. In addition, American combat swimmer teams from Naval Combat Demolition Units conducted nighttime reconnaissance on possible landing sites, mapping underwater obstacles and helping to clear obstacles during the invasion.