After the success achieved by the surface ships in the Atlantic waters during the winter of 1940-1941, the German Naval High Command decided to launch a much more ambitious operation. The idea was to send to the Atlantic a powerful battle group comprised by the battleships Bismarck, Tirpitz, Scharnhorst and Gneisenau. These last two battleships were in Brest, in the occupied France, since 22 March, after a successful campaign of two months in the North Atlantic under the command of the Fleet Chief, Admiral Günther Lütjens, in which they sank or captured 22 ships with a total tonnage of 116,000 tons. The Bismarck which had almost finished her trials would soon be ready for her first war mission. But her sister ship, the Tirpitz which had just been commissioned on 25 February still had to spend some months of training, and it was not probable that she would be ready for the spring. Moreover, the Scharnhorst had to enter dry dock in order to do some repairs in her machinery, and that would immobilize the ship at least until June.

On 2 April, the same day the Bismarck received her last two Arado 196, the High Command outlined the strategy to follow in its operation order (B.Nr. 1. Skl. I Op. 410/41 Gkdos Chefs.). With the Scharnhorst in dry dock and the Tirpitz not ready for action yet, the Bismarck and the heavy cruiser Prinz Eugen would be sent to the North Atlantic at the end of April under the command of the Fleet Chief. These two ships would be joined later by the Gneisenau sailing from Brest. The task of the German ships was to attack the convoys operating in the North Atlantic over the Equatorial line. Nevertheless, after the experience got with the Scharnhorst and the Gneisenau in the last months, now the enemy convoys were strongly protected by British cruisers or battleships. So if that was the case, the powerful Bismarck would take care of the escorting ship thus allowing the other ships to attack the convoy without any problem.

The British Admiralty was worried and suspected that the Germans were planning a big operation with surface ships in the Atlantic. The British knew about the presence of the Scharnhorst and the Gneisenau in Brest and the danger that would represent their sortie to the sea. Therefore they made arrangements to immobilize the German battleships through air bombings. On 6 April, a Coastal Command Beaufort plane (Lieutenant Kenneth Campbell) of the 22º Squadron scored a torpedo hit on Gneisenau's stern. The British aircraft was shot down by the anti-aircraft batteries, but the Gneisenau was damaged and had to enter dry dock for repairs. A few days later, during the night of 10/11 April, the battleship was hit again. This time by four bombs during a bombing by the RAF, and this forced to lengthen the repair work during months. Therefore, only the Bismarck and the Prinz Eugen would be ready to sail and attack enemy merchant shipping in the spring.

So it seems that there were more than enough reasons to cancel Bismarck's departure and wait until the autumn for the Tirpitz or the battleships stationed in Brest to be ready. Also the short spring nights increased the possibility to detect the German ships before they could get into the Atlantic. Nevertheless, the idea to send the Bismarck and the Prinz Eugen to the Atlantic in the spring of 1941 was not bad at all. The United Kingdom was in a critical situation and five months of "relative calm" at sea would have only strengthened her position. We also have to take in consideration that this could be the last opportunity for German ships to reach the Atlantic and have some freedom of movement, since the war with the United States would have to come some day and then this task would be much more difficult if not impossible. It was also ironic maintain a ship with the potential of the Bismarck in her home base doing nothing. Grand Admiral Erich Raeder wanted to maintain the pressure on the British and decided to go on with the operation. The most important thing was that the two German ships could reach the Atlantic unnoticed. Then they could get lost in the immensity of the ocean and attack the enemy convoys.

Meanwhile, on 8 April, Admiral Lütjens had met the U-boat Chief, Vice-Admiral Karl Dönitz in Paris. Both Admirals knew each other well as they had coincided in several occasions before the war. At the conference they outlined the support that was to be given to the Bismarck by the U-boats. The U-boats would carry on as usual in their normal positions, but if any opportunity arose for a combined action with U-boats they should exploit it to the full. A U-boat officer was therefore assigned to the Bismarck.

On 22 April, Admiral Lütjens established the details of the operation now code named Rheinübung (Rhine Exercise). The departure of the German ships was imminent, but on 23 April, a magnetic mine exploded near the Prinz Eugen while on her way to Kiel, and because of the repair work the operation was delayed for some days. Three days later, on 26 April, Lütjens and Raeder met in Berlin to examine the situation. The Fleet Chief suggested Raeder the possibility to postpone the operation but finally agreed with the Grand Admiral's intentions to resume the battle of the Atlantic as soon as possible. On 5 May, Hitler visited Gotenhafen to inspect the Bismarck and the Tirpitz. Raeder was absent, and Lütjens received the Führer, but he didn't inform him about the next sortie of his ships. The departure of the Bismarck was again delayed on 14 May, this time because her port crane had to be repaired and therefore a couple of days more were lost. Finally on 16 May, Lütjens informed the High Command that the ships were ready, and the date for the beginning of Operation Rheinübung was established for 18 May.