'Whale' roadway section and buffer pontoon of the Second World War Mulberry Harbour


Heritage Category:
Listed Building
List Entry Number:
Date first listed:
Location Description:
Statutory Address:
East of the Royal Pier, Southampton, S014 2AQ


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Statutory Address:
East of the Royal Pier, Southampton, S014 2AQ

The building or site itself may lie within the boundary of more than one authority.

Location Description:
City of Southampton (Unitary Authority)
Non Civil Parish
National Grid Reference:


‘Whale’ roadway section and buffer pontoon from a Second World War Mulberry Harbour. Built in 1943-1944 and installed next to the Royal Pier, Southampton in 1950.

Reasons for Designation

The Whale roadway section and buffer pontoon of a Second World War Mulberry Harbour at the Royal Pier, Southampton are listed at Grade II for the following principal reasons:

Historic interest: * as a tangible reminder of the part played by the Mulberry Harbour in the success of Operation Overlord; * for their rarity as one of only four known surviving examples of a Whale section in Britain and possibly the only surviving example of a buffer pontoon; * as a reminder of the prominent role of the City of Southampton in the preparation and launching of Overlord.

Architectural interest: * for their innovative design.

Group value: * for the association with the Grade II listed Royal Pier and entrance building.


D-Day, 6 June 1944, was one of the most significant operations of World War II, defining the start of the final phase of the war in Europe. After two to three years of preparations, the assault phase of 'Operation Overlord', code-named 'Neptune', lasted for little over three weeks and by 30 June had landed over 850,000 men on the invasion beachheads in Normandy, together with nearly 150,000 vehicles and 570,000 tons of supplies.

Much of the success of Operation Overlord was due to the creation of a pre-fabricated harbour, code named ‘Mulberry'; built in sections and towed across the Channel. Two Mulberry harbours were proposed; one in the British sector on 'Gold' beach at Arromanches (Mulberry B); the other further west in the American sector on 'Omaha' beach (Mulberry A). Assembly started on 9 June and by the 18 June the two arcs of caissons were in place. The following day, however, a heavy storm wrecked the incomplete harbour on Omaha beach and severely damaged that at Gold beach. What could be salvaged from Omaha beach was transferred to the British sector. The loss of Mulberry A meant that the capture of the port of Cherbourg now became a strategic imperative for the Americans, although the caissons still provided a sheltered anchorage for transhipment of supplies directly onto the beach. The Mulberry harbours, however, had fulfilled their strategic function in allowing a landing without the necessity of having to immediately capture a heavily fortified port in order to re-supply the invasion. Winston Churchill stated that the harbours were 'a principal part of the great plan', and were decisive in the first days of the invasion. Originally intended to function for a period of 90 days, the surviving Mulberry A harbour eventually continued in use into the winter of 1944 when the facilities at Antwerp were captured, allowing for a new line of supply to the allied armies in Belgium and northern France.

Churchill had conceived of creating rudimentary harbours by sinking sand-filled barges during World War I. Although the concept was not used at that time, Churchill remained a strong advocate of the potential of artificial harbours. In 1941 the War Office established a department to evaluate and refine artificial harbour designs, under Major General D J McMullen, Brigadier Bruce White and Major Cornick R E. The final decision to proceed with the artificial harbours was, however, not taken until the Quebec Conference in late August 1943, with designs only begun in October and construction in December. This allowed only a very short, six month, construction period.

The artificial harbours were made up of three structures: outer breakwaters, pier heads and floating roadways that connected to the shoreline. Each component was given a codeword to maintain secrecy for the operation. The breakwater comprised three elements: a floating outer line of connected hollow steel breakwaters (Bombardons); the Phoenix caissons, which were very large rectangular concrete structures that were airtight enabling them to be sunk and re-floated; and an assembly of 60 obsolete vessels that would be scuttled to form a protective line of block ships (Gooseberries). The pier heads were made up of floating pontoons (Spuds), which were attached to legs that permitted the pier head to move up and down with the tide. A total of 10 miles of floating roadways or bridges (Whales), supported on floating pontoons (Beetles), connected the pier heads to the shore.

The Whales were designed by Colonel Steer Webster. Orders were placed for the construction of the whales in June 1943 and components were farmed out to about 200 companies throughout Britain. For reasons of secrecy the Whales were only assembled at two Royal Engineer depots, principally at Marchwood, Hampshire. The Whales were specially designed to allow structural flexibility, both on installation and as they were towed across the English Channel in 500ft sections, when 40% were lost.

Each bridge span consisted of two 80ft (24m) long steel box trusses with a 10ft (3m) wide steel plate roadway bolted to cross girders. Each section weighed 30 tons. One in six of the bridge spans had sliding telescopic joints at the centre to allow for adjustments in length.

After Mulberry was dismantled in late 1944, some Whale sections were subsequently used as bridges in Normandy or else towed back to Marchwood for dismantling and storage. The Whale and buffer pontoon at the Royal Pier Southampton were installed in 1950 and originally comprised two sections of Whale, although only one survives today. It was used as a roadway linking the landing stage for the Isle of Wight ferry. It is unclear whether it comprised spare sections or those brought back from Normandy and stored at Marchwood. The only other Whale section known to survive in England (apart from two sunken sections identified off Selsey Bill in West Sussex), is at the Imperial War Museum at Duxford where a restored example was returned from France in 2016 where it had been used as a bridge at Pont-Farcy in Normandy.

The buffer pontoons, also termed artificial beaches or, by the Americans as 'floating door stops', were specially designed disembarkation platforms with a sloping profile for the use of landing craft. They were specifically part of the LST (Landing ShipTank) Pier and a pair of buffer pontoons were placed either side of a lateral 'spud' pontoon to enable two LST's to discharge their cargo. The buffer pontoons were joined to the spuds by hinged attachments with the thin edge of the wedge below the water line so the LST could run up onto the artificial 'beach' before lowering their ramps. The only other possible survival of a buffer pontoon known in England is a sunken example, also off Selsey Bill, although this may have been misidentified.


MATERIALS: the Whale is of steel girder construction, the buffer pontoon is a steel plate over a steel frame.

DESCRIPTION: WHALE: the reused whale is located immediately to the east of the C19 Royal Pier. The south end rests on the buffer pontoon. It provided a road linked to a landing stage for the Isle of Wight ferry and originally comprised two sections, one of which has been removed. It consists of two parallel rhomboid trusses connected by cross girders below the roadway. Each truss is 24m long and consists of five upright girders with diagonal braces with round cut-outs. At either end the trusses are strengthened by shaped steel plates with three elliptical cut-outs. The various members are connected by heavy steel bolts. At each end of the trusses are ball and socket joints connected to a cross girder. These allowed up to 40 degrees of vertical movement between adjoining sections of roadway. The sockets are protected by an arched guard piece.

The decking of wooden planking is not original. Running down the centre of the structure is a raised metal footbridge with metal railings connecting to the landing stage, installed after the Whale ceased to be used for road traffic. A number of other later structures are attached to the whale including access gates and a steel plate ramp at the shore end and steel posts supporting lights on the western truss. These later additions do not contribute to the special interest of the structure.

BUFFER PONTOON: this comprises a hollow steel pontoon, octagonal in plan with a curved ramp edge and wedge-shaped section. The ramp is partly submerged. The deck has a number of mooring bollards and raised plates. On the rear edge are the large hinges which attached the buffer pontoon to the spud pontoon. Two lamp-posts and the steel superstructure supporting the raised footbridge are later additions and do not contribute to the special interest.


This building is listed under the Planning (Listed Buildings and Conservation Areas) Act 1990 as amended for its special architectural or historic interest.

End of official listing

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