At dawn on Sunday, 18 May, the increasing light revealed thick cloud cover over Gdynia. The wind was calm and the weather was well suited for leaving the Baltic port and commencing Operation Rheinübung. In the morning Lütjens gathered the two commanders, Lindemann and Brinkmann, on board the Bismarck. He wanted to make his intentions for the forthcoming operation clear. The plans that had been prepared previously were to be followed. The squadron would pass the Great Belt in Denmark and continue through the Kattegat and Skagerrak. Then, Lütjens would set course for the Korsfjord, near Bergen, where fuel oil would be topped up, to replace the quantity burned during the voyage from Gdynia. However, there was an alternative. If the weather proved favourable, Lütjens would choose to go for the tanker Weissenburg in the Arctic Ocean. Thereafter, the break-out attempt would be directed through the Denmark Strait, where the fog prevalent along the edge of pack ice could be used to advantage.169
The purpose of the operation would still be kept secret from the crews. They were to be informed that the squadron sailed for the North Sea. Not until Lütjens gave his final order for the break-out would his real intentions be revealed. Furthermore, Lütjens elaborated on the use that should be made of the sea planes carried by the Bismarck and Prinz Eugen. His instructions were obviously influenced by the experiences from Operation Berlin. He made it clear that the aircraft were not allowed to attack enemy ships and they were only allowed to start upon receipt of written orders.170
After about an hour the meeting closed. The weather cleared, but since they were a long way from British bases, it was more important that the weather made the task difficult for British reconnaissance aircraft during the following days. The decision to sail was abided by, and at noon the two German ships left Gdynia.
‘I wish you good hunting,’ Lütjens announced to the crew on board the Bismarck and the seamen unable to attend on deck heard him on the many loudspeakers within the battleship. Her orchestra played ‘Muß i denn…,’ a tune often performed when ships of the German Navy departed on long voyages.171 With hindsight, the music selection has been identified as a lapse in secrecy. To what extent the information may have affected subsequent events is unclear, but by itself it was not enough to justify British action. In any case the first part of the voyage was very short. The German ships just moved further out in the harbour. Still within sight of land, they took on more fuel oil. A mishap occurred when a hose broke. The consequence was that the Bismarck lacked about 200 tons of fuel oil when she and the Prinz Eugen weighed anchor later in the evening, under cover of darkness. Operation Rheinübung had begun, even though the two ships initially sailed separately.172
During the night, the ships ploughed forward on the Baltic to a point north of Cape Arkona, on the northern shore of the island of Rügen, where they converged and were joined by several destroyers, led by Commander Alfred Schulze-Hinrichs. At a speed of 17 knots the warships proceeded westward, until they reached a point northwest of the Island of Fehmarn, where the helm was shifted to continue north, towards the mouth of the Great Belt. The German naval staff had closed the strait for all civilian shipping during the night between 19 and 20 May, to allow the warships an unobserved passage.173
While the Bismarck and Prinz Eugen enjoyed the calm sea, other German units were busy gathering information. A Focke-Wulf Fw 200 had been sent to investigate the ice north of Iceland, but bad weather hampered the mission. Nevertheless, it seemed clear that there was no drifting ice within 130 kilometres of Iceland, a promising circumstance for Operation Rheinübung. A less comforting observation concerned eight Swedish fishing-boats in Skagerrak. If they remained there when Lütjens’ squadron sailed by, there was a serious risk of detection.174
At dusk on 19 May, Lütjens’ squadron approached the Great Belt and two hours after midnight they passed into the narrow strait, unfortunately slightly later than planned. As dawn broke on 20 May, the seamen on deck could see Fyn to the west and Sjælland to the east. The grey sky was at least some help to the Germans, as it reduced the morning light. It was a consolation for Lütjens and his staff, but also a grave disadvantage, as the same cloud cover extended all the way to Scapa Flow and prevented German aerial reconnaissance. Thus the Germans received no information on the Home Fleet and its whereabouts.175
As the Bismarck and Prinz Eugen continued northward, the cloud coverage gradually disappeared and the seamen on deck could see the small island of Anholt on the starboard. Lütjens and his staff had every reason to be worried. Everything that might increase the risk of discovery was disadvantageous.176 Müllenheim-Rechberg clearly recalled this part of the voyage: ‘If only we hadn’t had to steam in such clear view of the Swedish coast and among innumerable Danish and Swedish fishing boats. They seemed to be everywhere, these little white craft with their chugging motors, some of them bobbing up and down beside us.’177