'Elphenbein' was a German naval undertaking to provide a force of three U-boat’s to aid the blockade runner Rhakotis, laden with important raw materials and approaching Europe from the Far East (19 December 1942).
The 6,753-ton Rhakotis had departed Yokohama on 27 September as the last of a wave of German blockade runners which also included the 7,840-ton Tannenfels (departed Yokohama on 8 August), 5,567-ton Dresden (departed Yokohama on 20 August), 7,363-ton Kulmerland (departed Dairen), and 8,068-ton Regensburg (departed Kobe on 14 September).
After 'Ultra' intelligence had indicated that blockade runner was approaching the North Atlantic, the US submarines Barb, Blackfish, Herring and Shad, together with the Free Dutch Dolfijn, which were on passage to the Mediterranean, were ordered into a patrol line to intercept the ship. Problems with communications, however, led to a delay in establishing the line and it was a Short Sunderland four-engined flying boat which spotted and reported Rhakotis and another ship some 230 miles (370 km) to the north-west of Cape Finisterre.
On 1 January 1943 Rhakotis was intercepted by the British light anti-aircraft cruiser Scylla, and after the British warship had opened fire, the blazing Rhakotis was scuttled by her crew.