During the preparation for the landing in Normandy (Operation Overlord) in June 1944, the Allied strategists decided to set up in deep water off the Normandy coast two prefabricated artificial harbors allowing the arrival of reinforcements and equipment on the continent. These two structures represented a daring bet. They were manufactured and assembled in the United Kingdom before being towed to the Normandy coast in the Calvados department. The first of them bore the code name Mulberry A and was to allow the arrival of American troops on Omaha Beach in Vierville-sur-Mer. The second, Mulberry B, whose remains are still visible, ensured the landing of British troops on Gold Beach in Arromanches-les-Bains.