During WWII locations around Garlieston including the harbour and nearby Rigg Bay were test sites for three Mulberry Harbour prototypes. This area of the Solway Firth was selected because tide and seabed conditions were similar to those to be encountered in Normandy. In addition, the remote location meant that the trials could be undertaken in secret.
The Mulberry Harbour remains at Eggerness and Rigg Bay are now protected national monuments.
Mulberry Harbour testing at Garlieston
Clockwise from top left: 1) Swiss Roll sections are unfurled in Garlieston Harbour. 2) A section of Swiss Roll is unloaded at the harbour. 3) A section of floating roadway is tethered to the shore at Rigg Bay. 4) A section of floating roadway is assembled in Garlieston Harbour. 5) The Harbour that went to war — a ‘Spud’ pierhead and ‘Whale’ roadway off Portyerrock. 6) A Crusader tank tests the floating roadway off Portyerrock.
(For background see https://en.wikipedia.org/wiki/Mulberry_harbour)