At 02:00 on 19 May 1941, "Bismarck" and "Prinz Eugen" left Gotenhafen and proceeded through the Baltic Sea and out toward the Atlantic. Unknown to Lütjens, the British had intercepted enough signals to infer that a German naval operation might occur in the area. The German task force was first encountered by the Swedish seaplane-cruiser on 20 May heading north-west past Gothenburg. The British Admiralty was informed through a Norwegian officer in Stockholm who had learned of the sighting from a Swedish military intelligence source. Alerted by this report, British Admiralty requested air reconnaissance of the Norwegian coast. A Spitfire reconnaissance aircraft found and photographed the German task force in the Grimstad fjord (), near Bergen, at 13:15 on 21 May. On the evening of 23 May at 19:22, the German force was detected by the heavy cruisers and that had been patrolling the Denmark Strait in the expectation of a German breakout. The alarm was sounded and Lindemann announced at 20:30 over the intercom: "". (Enemy sighted to port. Engage!) "Bismarck" fired five salvos without scoring a direct hit. The heavily outgunned British cruisers retired to a safe distance and shadowed the enemy until their own heavy units could draw closer. However, "Bismarck"s forward radar had failed as a result of vibration from the heavy guns firing during this skirmish, and Lütjens was obliged to order "Prinz Eugen" to move ahead of "Bismarck" in order to provide the squadron with forward radar coverage.