Wrecked pontoon causeway of one of the "Mulberry" artificial harbours, following the storm of 19–22 June 1944.
By 9 June, just 3 days after D-Day, two harbours codenamed Mulberry "A" and "B" were constructed at Omaha Beach and Arromanches, respectively. However, a large storm on 19 June destroyed the American harbour at Omaha, leaving only the British harbour still intact but damaged, which included damage to the 'Swiss Roll' which had been deployed as the most western floating roadway had to be taken out of service. The surviving Mulberry "B" came to be known as Port Winston at Arromanches. While the harbour at Omaha was destroyed sooner than expected, Port Winston saw heavy use for 8 months—despite being designed to last only 3 months. In the 10 months after D-Day, it was used to land over 2.5 million men, 500,000 vehicles, and 4 million tonnes of supplies providing much needed reinforcements in France. In response to this longer than planned use the Phoenix breakwater was reinforced with the addition of extra specially strengthened caisson.
The Royal Engineers built a complete Mulberry harbour out of 600,000 tons of concrete between 33 jetties, and had 10 miles (15 km) of floating roadways to land men and vehicles on the beach. Port Winston is commonly upheld as one of the best examples of military engineering. Its remains are still visible today from the beaches at Arromanches, and a section of it remains embedded in the sand in the Thames Estuary, accessible at low tide, about 1 km off the coast of the military base at Shoeburyness. A Phoenix unit known as The Far Mulberry sank off Pagham and lying at about 10 metres is an easily accessible scuba diving site. Another unit is aground with a broken back just inside Langstone Harbour.
Harbour elements and code names
Below are listed brief details of the major elements of the harbours together with their associated military code names.
"Corn cobs" were block ships that crossed the channel either under their own steam or that were towed and then scuttled to create sheltered water at the five landing beaches. Once in position the "Corn Cobs" created "Gooseberries". The ships used for each beach were:
Utah Beach (Gooseberry 1): Benjamin Contee, David O. Saylor, George S. Wasson, Matt W. Ransom, West Cheswald, West Honaker, West Nohno, Willis A. Slater, Victory Sword and Vitruvius.