[citation needed] At 1:30am on 28 March 1942 Roy was on the deck of HMS Campbeltown, an old First World War Wickes-class destroyer, formerly USS Buchanan, with her Oerlikon 20 mm cannon blazing at the German guns only a few yards away.
[1] The kilt-wearing Roy, nicknamed "The Laird", and his 14-man assault troop were tasked with disabling two pump-house roof-top gun emplacements high above the quayside and securing a bridge to provide a route for the raiding parties to exit the dock area.
Roy and Sergeant Don Randall used scaling ladders and grenades to accomplish the former and, although depleted by casualties, they launched a head-on rush to secure 'Bridge G' (later known as Pont du Roi – Roy's Bridge) and form a bridgehead that enabled Captain Bob Montgomery and Lieutenant Corran Purdon and their demolition teams to exit the area.
[citation needed] The position was extremely exposed and with only the flimsiest cover they hung on for one and a half hours suffering casualties to half of the troop from a continuous fire that was directed onto them from unreachable guns on elevated positions on the far side of the St. Nazaire Submarine Basin, particularly two quadruple Oerlikons, and from ships in the Submarine Basin itself.
He was taken with other officers including Micky Burn, Bill "Tiger" Watson and Corran Purdon to Oflag IX-A, Spangenberg Castle.