With the planning of Operation Overlord at an advanced stage by the summer of 1943, it was accepted that the proposed artificial harbours would need to be prefabricated in the UK and then towed across the English Channel.

The need for two separate artificial harbours – one American and one British/Canadian – was agreed at the Quebec Conference in August 1943.
An Artificial Harbours Sub-Committee was set up under the Chairmanship of the civil engineer Colin R White (Sir Bruce White's brother) to advise on the location of the harbour and the form of the breakwater; the Sub-Committee's first meeting was held at the Institution of Civil Engineers (ICE) on 4 August 1943.
The minutes of the Sub-Committee's meetings show that initially it was envisaged that bubble breakwaters would be used, then block ships were proposed and finally, due to an insufficient number of block ships being available, a mix of block ships and purpose made concrete caisson units.

On 2 September 1943 the Combined Chiefs of Staff estimated that the artificial ports (Mulberries) would need to handle 12,000 tons per day, exclusive of motor transport and in all weathers.
On 4 September the go ahead was given to start work immediately on the harbours.
However, infighting between the War Office and the Admiralty over responsibility was only resolved on 15 December 1943 by the intervention of the Vice-Chiefs of Staff.
The decision was that the Admiralty managed the blockships, Bombardons and assembly of all constituent parts on the south coast of England.
Further the Admiralty would undertake all necessary work to survey, site, tow and mark navigation.

The War Office was given the task of constructing the concrete caissons (Phoenixes), the roadways (Whales) and protection via anti-aircraft installations.
Once at the site, the army was responsible for sinking the caissons and assembling all the various other units of the harbours.

For the Mulberry A at Omaha Beach, the naval Corps of Civil Engineers would construct the harbour from the prefabricated parts.

The proposed harbours called for many huge caissons of various sorts to build breakwaters and piers and connecting structures to provide the roadways.
The caissons were built at a number of locations, mainly existing ship building facilities or large beaches, like Conwy Morfa, around the British coast.
The works were let out to commercial construction firms including Wates Construction Balfour Beatty, Henry Boot, Bovis & Co, Cochrane & Sons, Costain, Cubitts, French, Holloway Brothers, John Laing & Son, Peter Lind & Company, Sir Robert McAlpine, Melville Dundas & Whitson, Mowlem, Nuttall, Parkinson, Halcrow Group, Pauling & Co. and Taylor Woodrow.
On completion they were towed across the English Channel by tugs to the Normandy coast at only 8.0 kilometres per hour (4.3 kn), assembled, operated and maintained by the Corps of Royal Engineers, under the guidance of Reginald D. Gwyther, who was appointed CBE for his efforts.
Various elements of the "Whale" piers were designed and constructed by a group of companies led by Braithwaite & Co, West Bromwich and Newport.
With the planning of Operation Overlord at an advanced stage by the summer of 1943, it was accepted that the proposed artificial harbours would need to be prefabricated in the UK and then towed across the English Channel.
The need for two separate artificial harbours – one American and one British/Canadian – was agreed at the Quebec Conference in August 1943. An Artificial Harbours Sub-Committee was set up under the Chairmanship of the civil engineer Colin R White (Sir Bruce White's brother) to advise on the location of the harbour and the form of the breakwater; the Sub-Committee's first meeting was held at the Institution of Civil Engineers (ICE) on 4 August 1943. The minutes of the Sub-Committee's meetings show that initially it was envisaged that bubble breakwaters would be used, then block ships were proposed and finally, due to an insufficient number of block ships being available, a mix of block ships and purpose made concrete caisson units.
On 2 September 1943 the Combined Chiefs of Staff estimated that the artificial ports (Mulberries) would need to handle 12,000 tons per day, exclusive of motor transport and in all weathers. On 4 September the go ahead was given to start work immediately on the harbours. However, infighting between the War Office and the Admiralty over responsibility was only resolved on 15 December 1943 by the intervention of the Vice-Chiefs of Staff. The decision was that the Admiralty managed the blockships, Bombardons and assembly of all constituent parts on the south coast of England. Further the Admiralty would undertake all necessary work to survey, site, tow and mark navigation.
The War Office was given the task of constructing the concrete caissons (Phoenixes), the roadways (Whales) and protection via anti-aircraft installations. Once at the site, the army was responsible for sinking the caissons and assembling all the various other units of the harbours.
For the Mulberry A at Omaha Beach, the naval Corps of Civil Engineers would construct the harbour from the prefabricated parts.
The proposed harbours called for many huge caissons of various sorts to build breakwaters and piers and connecting structures to provide the roadways. The caissons were built at a number of locations, mainly existing ship building facilities or large beaches, like Conwy Morfa, around the British coast. The works were let out to commercial construction firms including Wates Construction Balfour Beatty, Henry Boot, Bovis & Co, Cochrane & Sons, Costain, Cubitts, French, Holloway Brothers, John Laing & Son, Peter Lind & Company, Sir Robert McAlpine, Melville Dundas & Whitson, Mowlem, Nuttall, Parkinson, Halcrow Group, Pauling & Co. and Taylor Woodrow. On completion they were towed across the English Channel by tugs to the Normandy coast at only 8.0 kilometres per hour (4.3 kn), assembled, operated and maintained by the Corps of Royal Engineers, under the guidance of Reginald D. Gwyther, who was appointed CBE for his efforts. Various elements of the "Whale" piers were designed and constructed by a group of companies led by Braithwaite & Co, West Bromwich and Newport.
Mulberry harbour