Operation Accumulator was an Allied naval operation near the Channel Islands on the night of 12/13 June 1944, in support of Operation Overlord, the invasion of France. As part of Operation Fortitude, a series of deception operations had been used to divert attention from the Allied landings by suggesting that a second invasion force was still waiting to land. This caused the defenders to divert their forces from the fighting in Normandy, holding them in reserve for an invasion in the Pas de Calais, to the east.