Monument record MDO29764 - Phoenix caissons, Castletown, Portland

The site of a group of Second World War Phoenix caissons is visible on aerial photographs of the 1940s to the north of Castletown, Portland. Phoenix caissons formed the main breakwater for Mulberry harbours. The caissons were probably associated with the seaplane base HMS Sereptia.

'Two 'Phoenix' units of a World War II floating harbour which were produced to assist in the D-Day landings and Normandy invasion of 1944. Constructed of reinforced concrete, eight of these units were located in Portland Harbour in 1946 to provide protection for the construction of a new pier; two of these now remain, permanently moored, and lying due north-south, about 115 metres north of Castletown Pier. Each unit is circa 60 metres long by 18 metres wide, and 15 metres high. Most of these floating harbours, or "Mulberry Harbours" as they were code-named, were towed across the English Channel to serve the D-Day landings on 6th June 1944 on the Normandy beaches; these two sections are appropriately sited in Portland harbour as a reminder of this remarkable enterprise. (1)(2) Not charted by UKHO. (3) The site of a group of Second World War Phoenix caissons is visible on aerial photographs of the 1940s to the north of Castletown, Portland. Phoenix caissons formed the main breakwater for Mulberry harbours. The caissons were probably associated with the seaplane base HMS Sereptia. (1) Two caissons are currently moored in the harbour (see MDO6597-8). This site was digitally plotted during the South West Rapid Coastal Zone Assessment Survey (Dorset).

Record last edited

Jul 26 2023 10:09AM