On 23 April, while passing through the Fehmarn Belt en route to Kiel, "Prinz Eugen" detonated a magnetic mine dropped by British aircraft. The mine damaged the fuel tank, propeller shaft couplings, and fire control equipment. The planned sortie with "Bismarck" was delayed while repairs were carried out. Admirals Erich Raeder and Günther Lütjens discussed the possibility of delaying the operation further, in the hopes that repairs to the battleship would be completed or "Bismarck"s sistership would complete trials in time for the ships to join "Prinz Eugen" and "Bismarck". Raeder and Lütjens decided that it would be most beneficial to resume surface actions in the Atlantic as soon as possible, however, and that the two ships should sortie without reinforcement.