Military History | Arromanches-les-Bains — What the Harbour's Own Operators Counted

The first stores crossed the piers at Arromanches on 10 June 1944, four days after the landings. The harbour had been towed over the Channel in pieces and sunk into the bay off the Gold sector: a breakwater of Phoenix caissons — hollow concrete boxes that the Supreme Headquarters' own report describes in six sizes, the largest of several thousand tons, each needing two tugs to move — and behind them floating roadways running out to pierheads that rose and fell on legs planted in the sand.

Nine days after it opened, a gale blew for four days from 19 June. The American harbour off Saint-Laurent was wrecked. Rear Admiral Alan G. Kirk, commanding the Western Naval Task Force, judged it a total loss and decided against rebuilding, a finding recorded in the United States Army's official logistics history. Arromanches held, but not intact; the SHAEF report notes the total loss of its deep-water breakwater.

That report, compiled for the Supreme Headquarters' supply staff and dated 5 November 1944, is the closest thing to an audit the harbour has. From 10 June to 31 October it counts 628,000 tons of stores, 40,000 vehicles and 220,000 troops across the piers, and it gives the share: 35 per cent of British stores, 17 per cent of British vehicles, 23 per cent of British personnel. The rest came over open beach. Closure was planned for 1 December.

The caissons are still there. A survey commissioned by the Région Normandie found eleven of them in sound condition and sixty-seven in ruin, seawater reaching the steel inside the concrete, and expected none to be sound by 2075.

📸 Cover: the Phoenix caissons of Mulberry B in the bay off Arromanches, seen from the cliff, photograph by Héric SAMSON, CC BY-SA 3.0 via Wikimedia Commons. Second image: an overhead survey view of a broken caisson, Benjamin Simon (IFREMER), 9 March 2026, CC BY 4.0.