Operation Enthrone

This was a British naval undertaking to mark the northern edge of the German minefields off the coast of Normandy on the north coast of German-occupied France with F.H.830 underwater sonar beacon marker buoys (31 May 1944).

The operation successfully deposited 10 sonic buoys to become alive on the day before 'Overlord' to guide the motor launches which would in turn serve as the marker boats allowing the minesweepers to start their sweeping of the lanes required by the assault forces from exactly the correct positions.