On 12 April 1904, two Russian pre-dreadnought battleships, the flagship Petropavlovsk and the Pobeda, slipped out of port but struck Japanese mines off Port Arthur. The Petropavlovsk sank almost immediately, while the Pobeda had to be towed back to port for extensive repairs. Admiral Makarov, the single most effective Russian naval strategist of the war, died on the battleship Petropavlovsk.