Early in 1941 a new department within the War Office was set up code named 'Transportation 5' (Tn5) under Major General D J McMullen. It had responsibility for port engineering, repairs and maintenance. The Mulberry project and the need to construct sufficient embarkation points on the shores of the UK, soon became its top priorities. Under the command of civil engineer Bruce White their first project was to construct two military ports in the Clyde estuary one of which was the Gare Loch. There were many meetings with the Americans about the options to provide sheltered harbours.... sunken ships, concrete caissons, concrete pontoons, collapsible canvas floating barriers and Pykrete to name but some. There was scepticism on both sides of the Atlantic and some believed that Mulberry was even more fanciful an idea than Pykrete! To overcome the doubters in the ranks of the high-powered entourage, accompanying him to an important meeting in Quebec aboard the Queen Mary, Mountbatten called them to a meeting in one of the ship's bathrooms! There they saw a partially filled bath, 40 or so ships made out of newspaper and a Mae West lifebelt. Half the 'fleet' was placed in the bath and the most Junior officer present in the crowded bathroom, Lt Cmd Grant of the RN, was asked to make waves with the back of a brush. In no time the vessels sank. The demonstration was run again this time with the fleet floating inside the Mae West. To the immortal command "More waves please Lieutenant Grant" the heavily braided onlookers saw that all the vessels survived. One USA sceptic, Admiral John Leslie Hall Jr., US Navy Commander, was scathing of the idea, predicting that the Mulberries would never stand up to the rigours of the English Channel and, in any event, he could unload 1000 LSTs at a time on open beaches... more than enough to supply the advancing Allied forces. His prediction was, at least in part, later proved to be correct in the case of Mulberry A (details below). But the balance of opinion was in favour of the project and approval was given to proceed. The task of progressing the idea was given to Mountbatten's Combined Operations. He soon realised, however, that the resources needed were way beyond those of his command and he contracted out the operational aspects to the War Department.
Three designs were selected for further evaluation. The first from the War Office was for flexible steel bridges on pontoons of steel or concrete with pier-head units on adjustable legs to take account of the tides. The second from the Admiralty was a flexible floating construction of timber and canvas held together with steel cables and similar in appearance to a Swiss Roll in its stored condition. The third from Iorys Hughes envisaged the use of steel bridges to be mounted on concrete caissons and floated to the sites and sunk in position. Initially none were to be protected by breakwaters.
The search was on for 'test' beaches with characteristics similar to those off Normandy - flat, sandy, remote and sparsely populated to ensure an effective security cordon. After exhaustive surveys, Wigtown Bay on the Scottish side of the Solway Firth with its nearby harbour of Garlieston, was chosen.
The whole area from Garlieston to the Isle of Whithorn (not an island!) was declared off limits to all except local fishermen. Work started on the construction of a military camp at Cairnhead to accommodate the increasing numbers of engineering personnel
(Sappers) with an additional 200 men being accommodated in the village hall in Garlieston. The prototypes were constructed at "the Morfa," Conwy in North Wales where over 1000 local and outside labour was drafted in for the purpose. The Morfa area was transformed into a huge construction site. Hughes' three 'Hippo' caissons were towed to the site in Rigg Bay near Garlieston. Two 'Croc' roadways were attached to the metal bars on the Hippos and various combinations were tested in a variety of weather and tidal conditions including the driving of fully laden vehicles across the roadway. The testing proved invaluable since the behaviour of the components could be analysed and corrective action taken where necessary. One such problem was that the floating piers did not rise and fall with the tide as predicted but Hughes found a solution in the provision of adjustable spans between the Hippos and the roadway. A more serious problem was the unexpected pitching and yawing of the Hippos causing the attached Croc roadways to buckle. Hughes proposed the construction of Hippos of diminishing size on which the roadways would sit. Hughes' design was not alone in experiencing problems. When the 'Swiss Roll' roadway was tested with a 3-ton tipper truck the roadway sank in under two hours. Adjustments were made but further tests in the open sea confirmed that the heaviest load that could be carried was 7 tons - far below what was necessary for the movement of tanks. The Swiss Roll roadway design was soon abandoned. Churchill's memo of 30th May 1942 to Lord Mountbatten:
"Piers for use on beaches. They must float up and down with the tide. The anchor problem must be mastered. Let me have the best solution worked out. Don't argue the matter. The difficulties will argue for themselves." I have been a Chartered Surveyor for over 50 years and I cannot remember seeing such a complete and concise specification for such a huge project than that memo from Churchill. Progress at first was slow as discussions on competing ideas by the many interested parties were considered. Churchill was irritated by the apparent lack of progress and penned a number of increasingly irate messages culminating in the following on the 10 Mar 1943. "This matter is being much neglected. Dilatory experiments with varying types and patterns have resulted in us having nothing. It is now nearly six months since I urged the construction of several miles of pier." Some organisational changes were made to "get a grip" on the project. These early designs did not envisage protective breakwaters but it became clear that an area of calm water would be required.. In addition to the breakwaters included in the final plans consideration was also give to "bubble breaker" and "lilo".... the former involved pumping high pressure air along perforated pipelines causing a large volume of compressible air in the sea sufficient to absorb the power of heavy breakers. The latter were large canvas bags extending some 4m below the waves and 3m above. They were inflated to low pressure and operated on a similar basis to the bubble breaker in that they would absorb the power of the waves by allowing the air they contained to be compressed. On conclusion of the tests a final design was decided upon. There would be two harbours each comprising two breakwaters, offshore and flanking, made from hollow ferro-concrete caissons based on Hughs' Hippo designs. To provide extra protection 70 obsolete merchant and navy vessels (block-ships) would be sunk to fill gaps in the protection provided by the caissons. Inside the resultant protective cordons there would be pier-heads connected to the shore by floating steel roadways. In view of Iorys Hughes' commitment to the project and expertise he was invited by Churchill to serve the project as a consultant.
Mountbatten's ideal specification was for a pier a mile long that could withstand gale force winds and be capable of berthing large coasters. To do this the artificial harbours would need to provide sheltered conditions and be larger than the port of Dover, which had taken 7 years to build in peacetime! Within the sheltered areas stable-floating quays would be located some distance from the beaches to provide sufficient water depth (6.7 meters) for the docking vessels. These quays would be linked to the beaches by floating roadways to allow the discharged goods and equipment to be transported ashore in fleets of lorries. Two harbours would be required - Mulberry A for the USA beaches of Omaha and Utah and Mulberry B for the British and Canadian beaches of Gold, Juno and Sword. The designs would allow for the floating caissons to be secured in place in four days. Each harbour would have a capacity of 7000 tons of vehicles and supplies per day.
For security reasons randomly selected codes were used to describe the various components of the two Mulberry Harbours viz.
• Bombardons - floating breakwaters comprising huge, metal, crucifix shaped structures ballasted and firmly anchored in place. They were the outermost barrier and therefore the first line of defence against rough seas.
• Phoenexes - 146 concrete caissons 60 metres long, 18 metres high and 15 metres wide making up 9.5 kilometres of breakwater. They were airtight floating cases open at the bottom with air-cocks to lower them to the seabed in a controlled fashion. Around 2 million tons of steel and concrete were used in their construction.
• Gooseberries - 70 obsolete merchant vessels (block ships) were amassed at Oban on the west coast of Scotland, stripped down, ballasted and primed with explosive scuttling charges The vessels sailed under their own steam and were sunk in 5 locations including the 2 Mulberry harbours.
• Pierheads were located at the seaward end of the roadways. Each stood on four legs called (Spuds) with a platform that could be raised and lowered with the tide by means of electric winches. 23 were planned for of which 8 were spares.
• Beetles - concrete and steel floats or pontoons to support the roadways. Each capable of taking the weight of 56 tons + 25 tons (being the weight of a tank).
• Whales - 16 kilometres of roadways.
• Buffer - approach span from the floating roadway to beach.
• Rhino - power driven pontoon on which cargo was brought ashore. The final configuration of all these units when assembled and positioned can be seen in the following photograph although the Bombardons were too far out to be here:-