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Destruction of Mulberry-A in Fierce Storm - WWII

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Variable English Channel Weather

Damaged Whale roadways after fierce storm which destroyed the American Mulberry A harbor. Normandy, WWII.
Damaged Whale roadways after fierce storm which destroyed the American Mulberry A harbor. Normandy, WWII.

The English Channel weather was highly variable and subject to strong tides. The weather was both a friend and foe to the Allies participating in Operation Overlord — the invasion of Normandy. D-day itself was postponed one day due to bad weather, but with a break in the storm, General Eisenhower ordered the operation to commence the following day, on June 6, 1944.1

The Germans, believing that an Allied invasion would not be attempted during this weather, let down their guard, and German Commanders left their headquarters to attend war games in Rennes. Field Marshall Rommel, one of the top commanders in charge of the defense of Normandy, headed for Germany to celebrate his wife's birthday.

Fierce three day storm destroys Mulberry A

Construction of the Mulberry harbor continued for first days of the invasion. The Gooseberry blockships, had been added to the design because of concern as to how the Phoenix caissons would fair in the giant waves brought on by Channel storms. And on June 19, D-day plus 13, a fierce storm began which lasted for three days and was reportedly the strongest summer storm in forty years. It caused much damage to the in-progress Mulberry harbors. Image above shows a wrecked pontoon causeway  from the American Mulberry A artificial harbor at Omaha, following the storm of June 19, 1944 which destroyed the Mulberry A harbor.

The storm broke loose the Bombardon, (an outer ring of floating breakwater) and it was free to crash into the remaining harbor structures for the duration of the storm. At the American Mulberry A, several Phoenixes were badly damaged. Barges and other craft inside the harbor were thrown about by the giant waves. These vessels inflicted much damage as they repeatedly crashed into the whale roadways. By the end of the storm, Mulberry A was considered a complete loss, and any salvageable harbor components were sent to British Mulberry B, which was somewhat sheltered by a reef and suffered less damage. But most of the equipment and harbor components which were in transit were lost and the continued rough water caused delays in transporting remaining loads.

Tonnage unloaded with or without Mulberry Harbor

The surviving British Mulberry B was eventually able to unload 6,000 tons per day while the Americans landed 15,000 tons a day at Omaha and 8,000 at Utah without an artificial port.2 According to Chester Wilmot,



Undismayed by the destruction of their artificial harbour, the Americans applied to the development of the Omaha and Utah anchorages their tremendous talent for invention and organization. In defiance of orthodox opinion they beached coasters and unloaded them direct into Army lorries at low tide.…. during July the Americans here handled more than twice the tonnage which passed through the British Mulberry3.

Although the Mulberry harbors were planned for use until a port was captured, the British Mulberry B (nicknamed Port Winston) continued to be used long after the ports of Cherborg and La Harvre were taken.


1 The next date which would have been considered would have been June 19th, the date having the next appropriate low tide. This turned out to be in the middle of the fierce storm which destroyed the Mulberry A harbor.

2Yves Buffetaut, D-Day Ships – the Allied Invasion Fleet. June 1944, London: Conway Maritime Press, p.133.

3 Chester, Wilmot , The Struggle for Europe. Hertfordshire SG: Wordsworth Editions, 1997, p.387.