50th division infantry advancing near St Gabriel, 10 km from the landing beaches. 6 June 1944. Source: Imperial War Museum
It had a double breakwater, the first exterior one floating, the second interior one fixed, comprising concrete caissons and floating jetties running from the beaches to the jetty heads where ships could stay moored no matter what the movements of the tide. The harbour, prefabricated in England, was brought to Arromanches at a speed of 7 km an hour. Its installation began on 7 June. Sixty ships were run aground and one hundred and forty-six caissons were installed in less than ten days.
Aerial view of Mulberry artificial harbour at Arromanches, September 1944. Source: Imperial War Museum
In one hundred days, Port ”Winston”, named after Prime Minister Winston Churchill, with its 12-kilometre roadstead, could receive the largest ships and was able to land 2,500,000 men, 500,000 vehicles and 4,000,000 tonnes of materiel. Designed to last for the three months of summer, it continued to be used for eight months.
Trucks and troops landing at Mulberry B, July 1944. Source: Imperial War Museum
Many vestiges of this construction can still be seen on the beach of Arromanches.
Mulberry Bridge. Source: Creative Commons Licence
Vestiges of the ”Mulberry B” harbour at Arromanches-les-Bains, created during the Normandy landing in 1944. Source: Creative Commons Licence