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Gooseberry Blockship Breakwater - WWII

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Gooseberry Blockships Add to Mulberry Breakwater

Gooseberry blockships forming breakwater
Line of sunken Corncob blockships to create the Gooseberry breakwater - WWII, Normandy.

The first components of the Mulberry harbor to arrive at Normandy were ships which were to be sunk as blockships. It was feared that the Phoenix breakwaters might not survive the fierce storms common to the area so part of the Mulberry breakwater was to be composed of old ships (code named corncobs), sunk in a row as blockships, (code named Gooseberry).

Fifty-five old cargo ships, (twenty-three of them American) and four old warships were used to create five Gooseberry breakwaters (one for each beach) with only one not crossing the Channel under her own power. U.S. Navy photo above shows a line of sunken blockships which made up the Gooseberry breakwater.

Corncob ships for the Gooseberry Breakwater

Line of sunken blockships (Gooseberry) and concrete Phoenixes created a calm harbor the size of Dover.
Line of sunken blockships (Gooseberry) and concrete Phoenixes created a calm harbor the size of Dover. Note still water inside.

These individual ships, code named corncobs, began to arrive on the coast of Normandy on June 7, 1944 as the first components of the Mulberry harbor. The corncobs had been stripped and ballasted and were sunk in place by explosive charges in water three fathoms (18 feet) deep, which could give shelter to vessels with shallow draft. The breakwater created by the blockships and the concrete Phoenixes created the calm water necessary for a harbor. This effect can be seen in the Royal Navy photo to the right, where the water is visibly more still above the line of Phoenixes and blockships.

It was also realized that the blockships could be used as facilities for first aid, repairs, and fueling, and accommodations for the crews of the assault craft.1

Along with the concrete caissons which accommodated ships of up to 30 feet draft, the combined breakwaters helped create a deep water port approximately the size of Dover. These ships drew enemy fire as they arrived (mistakenly thought to be troop transports) and as they were scuttled with explosives, the German's first reaction was that they had struck a mine.2 They soon learned otherwise.


1Guy Hartcup, Code Name Mulberry – The Planning – Building & Operation of the Normandy Harbours, South Yorkshire: Pen & Sword Military, 2006, p.75.

2John P. Taylor, The Prefabricated Port of Arromanches – Mulberry B, p.6.