Derfflinger had capsised on sinking off the Island of Cava and the salvage of the largest of the upturned wrecks was deferred until easier targets had been raised. Metal Industries brought her to the surface using a technique of airlock tubes and compressed air to allow most of the interior patching to carried out above water level. The repaired hulk was raised in late August 1939 just as an old adversary, HMS Iron Duke arrived in Scapa as Headquarters Ship! Once Derfflinger had risen to the surface of the Flow, the tall airlock tubes were shortened to maintain stability and a compressor house and workmans' hut were added (as modelled) but Metal Industries's staff and equipment were requisitioned for the war effort so the wreck was towed to shallow water off Little Rysa, north of Lyness, and left in care and maintenance until a drydock could be spared to complete the scrapping after the end of the war. Derfflinger was the last major warship to be salvaged from Scapa Flow.