The German pocket battleship Admiral Graf Spee had raided shipping in the South Atlantic before it was scuttled off Uruguay’s Platte River on December 17, 1939. Survivors from merchant ships she had sunk had been transferred to one of her supply ships—Altmark—before the pocket battleship encountered the Royal Navy. The Altmark, commanded by Captain Heinrich Dau, headed back to Germany with its cargo of prisoners after the demise of the Admiral Graf Spee and entered Norwegian territorial waters on February 14.
The Norwegians had their suspicions about the ship’s cargo but allowed it to proceed along the coast under naval escort. The ship flew the German naval flag, but despite this fact, Dau allowed three visits by Norwegian naval personnel on February 15. The German captain reported that the ship had participated in exercises in the Atlantic and was on its way from Port Arthur, Texas to Germany with a cargo of 8,500-tons of oil, that the ship was armed with 20mm anti-aircraft guns, but that these were stowed away before entering Norwegian waters.
Rear Admiral Carsten Tank-Nielsen, the commander of Norway’s 2nd Naval District, was in a dilemma. If Altmark was a merchant ship, it had the right, under the neutrality regulations, to sail through the restricted area around Bergen after being inspected. A warship, on the other hand, could not sail through the area. Classified as a naval auxiliary, the ship did not fit neatly into either of the two categories.
The Norwegian destroyer Garm, with Admiral Tank-Nielsen aboard, and the minelayer Olav Tryggvason intercepted Altmark well within the restricted area, escorted by the torpedo boat Snøgg. The acting chief of staff of the naval district and Snøgg’s captain boarded Altmark and conferred with Captain Dau. The Norwegians informed Dau that either he had to submit to a search or he would not be allowed to proceed through the restricted area. Captain Dau stated that the ship was a naval auxiliary and he would not permit a search. He was then ordered to take his ship out to sea, around the restricted area.
While this conference was underway, the Germans broke radio silence and sent a report to the German Embassy in Oslo. Norwegian naval communicators intercepted the radio message and the military control office in Oslo stopped the telegram from reaching the German Embassy. Captain Dau was admonished not to use his radio while in Norwegian waters. The German captain apologized but asked the Norwegians to notify the German Embassy that he had refused inspection and was taking his ship out to sea. Admiral Tank-Nielsen agreed to this request. Altmark withdrew from the restricted area to await an answer from the German Embassy. Norwegian warships remained in the vicinity to ensure that the German ship did not reenter the restricted area.
The destroyer Garm had been close enough to Altmark for sailors to report that SOS whistle signals were heard from the German ship and that white handkerchiefs had been displayed at the portholes. Garm also reported that the Germans had started up the on-board cranes and other machinery, obviously in an attempt to drown out the signals.
Admiral Tank-Nielsen sent the following message to the Norwegian Naval Staff: “The ship has refused supplemental visitation and its passage through the restricted area has been denied. Probably prisoners aboard. Inform the Commander-in-Chief.”19 The telegram reached Admiral Diesen at 1554 hours. Diesen conferred with the Norwegian Foreign Office. Both the Foreign Office and Admiral Diesen appear to have felt there had been enough visitations to the German ship, and that Admiral Tank-Nielsen was not handling this problem in accordance with supplemental instructions after a somewhat similar situation in November 1939.20 Diesen and the Foreign Office decided to send the German ship on its way at once. The Norwegians were eager to get this embarrassing and potentially dangerous ship out of its territorial waters as quickly as possible.
The report from Garm about suspicious activities aboard Altmark did not reach the Norwegian naval headquarters until after Admiral Diesen’s decision, but he stated later that receipt of the report would not have altered his decision. Admiral Tank-Nielsen was ordered to let Altmark pass in its capacity as a naval auxiliary and to provide an escort. The passage through the restricted area was accomplished in darkness, an action contrary to the navy’s own neutrality regulations.
Meantime, a report of Altmark’s presence in Norwegian waters had reached Rear Admiral H. Boyles, the British Naval Attaché in Oslo. Boyles passed this report on to the British Admiralty. Churchill recognized the potential opportunities in the situation and acted quickly. He instructed Admiral Pound that he should not hesitate “… to arrest Altmark in territorial waters should she be found. The ship is violating neutrality in carrying British prisoners of war to Germany…. The Altmark must be regarded as an invaluable trophy.”21
Three reconnaissance aircraft from Coastal Command were dispatched to locate Altmark. She was sighted in Norwegian waters south of Stavanger. The escorting Norwegian patrol boat Firern had no antiaircraft guns and could only signal the British aircraft that they were violating Norwegian airspace, and warn them to stand off.
A British destroyer flotilla of six ships commanded by Captain Philip Vian (later Admiral of the Fleet) in the destroyer Cossack, intercepted Altmark, now escorted by the Norwegian torpedo boat Skarv, outside the entrance to Jøssingfjord, halfway between Egersund and Flekkefjord. Three destroyers made the initial intercept: Cossack, Intrepid, and Ivanhoe. At first, they stopped short of Norwegian territory and signaled Altmark to proceed on a westerly course, out of Norwegian waters. Altmark ignored the signal and proceeded on its previous course. At that point, Intrepid and Ivanhoe entered Norwegian waters despite protests from the Norwegian torpedo boat. Ivanhoe tried to position itself to block Altmark but the Norwegian torpedo boat
