(Above) The Germans erected a sign to mark the occasion in 1940 when the Altmark was "set upon by a British sea-pirate"
A captured Nazi sign commemorating a buccaneering World War Two raid by the navy has been donated to the National Museum of the Royal Navy at Portsmouth Historic Dockyard.
The Altmark Incident was an early wartime morale boost for Britain which saw a boarding party from the British destroyer, HMS Cossack, release 299 British prisoners from the German ship Altmark in a Norwegian fjord.
A supply tanker to the famous German pocket battleship Graf Spee, Altmark was carrying a cargo of British merchant seamen prisoners, which it had picked up as survivors from ships sunk by the Graf Spee. But following the pocket battleship's sinking at the Battle of the River Plate in Argentina in December 1939, the Altmark slowly made its way home – reaching Norwegian waters in February 1940.
Around the same time a small flotilla of British destroyers set sail from Scotland, ostensibly to carry out ice reconnaissance. After a tip-off from the British naval attaché in Oslo, the ice flotilla led by the British cruiser Arethusa and five destroyers moved to trap the German vessel at Jossingfjord.
(Above) The sign is now at the National Museum of the Royal Navy at Portsmouth
Attempts at negotiations with the Norwegians to force Altmark from the fjord failed, so the Royal Navy took matters into their own hands and sent in a party from HMS Cossack to board the German vessel.
After a short engagement, which reputedly involved both bayonet and cutlass, five Germans were killed and several others wounded. A Royal Navy sailor then opened up the ship's hold and shouted down: "Are there any Englishmen down there?". When the reply was a resounding yes, the now famous words were uttered "then come up, the Navy's here".
Following the German occupation of Norway, a commemorative sign was erected by the indignant Germans, saying: "Here on 16th Feb. 1940 the Altmark was set upon by a British sea-pirate."
British airborne forces liberated the double-sided sign in 1944 and gave one side to the commander of the flottila Admiral Vian in commemoration of his daring feat. This has now been donated to the National Museum of the Royal Navy for future public display through the HMS Cossack Association.
Visitors to Heritage Open Days will be able to see the sign during a free behind-the-scenes tour of the collection on Saturday and Sunday, September 11 and 12 at 11am, 1pm and 3pm . Places are limited, phone 023 9272 8060 to reserve a place.