THE ALTMARK INCIDENT. The Altmark was a tanker and supply ship serving the German battleship 'Graf Spee'. Survivors from the nine ships sunk by the Graf Spee were now Prisoners of War on the Altmark. On 16th of February, 1940, after a hectic search by The Royal Navy, the Altmark was located in the Jossing Fjord on the southern tip of Norway where she had taken refuge from the pursuing British destroyers. In violation of international law, the British destroyer HMS Cossak entered the Fjord and with an armed party boarded the Altmark. After a brief skirmish the crew was overpowered and 299 British prisoners freed. Members of the Altmark’s crew were machine-gunned as they fled across the ice during the boarding. It was this incident that caused Hitler to accelerate his plans for his occupation of Norway, believing that the British would not respect Norwegian neutrality.