Vian in the Jøssingfjord

The Altmark is a Kriegsmarine supply ship (8,116 tons), built in 1938 to support commerce-raiding operations in the Atlantic. From 23 August to 6 December 1939 she accompanied the Graf Spee on her Atlantic cruise, taking aboard the British crews of the nine merchantmen sunk by Langsdorff — 299 prisoners packed into her holds. After the end of the Graf Spee at Montevideo, the Altmark's captain, Heinrich Dau, must bring those prisoners back to Germany alone.

Dau chooses a bold route: head up the North Atlantic under a forged Norwegian identity, then run inside Norwegian territorial waters (neutral) to reach Wilhelmshaven. On 14 February 1940 the Altmark is spotted off the Lofotens by a British aircraft. From that moment the Royal Navy knows she is carrying prisoners and is in Norwegian waters. Diplomatic crisis.

The Norwegian authorities (Rear Admiral Carstens-Egeberg) inspect the Altmark at Trondheim on 15 February. The inspection is cursory: Dau claims the holds are empty (in fact 299 prisoners are locked inside). The Norwegian command accepts the declaration and authorises onward passage. Report to the British Admiralty: on 16 February Churchill (First Lord) is informed personally and orders Captain Philip Vian (commanding the 4th Destroyer Flotilla aboard HMS Cossack) to intercept the Altmark in Norwegian waters, in violation of neutrality — a major political decision taken on the spot.

Vian must choose how to intervene in the Jøssingfjord, where the Altmark has taken refuge.