On 3 May 1904, Admiral Togo made his third and final attempt at blocking the entrance to Port Arthur, this time with eight old transports. This attempt also failed, but Togo proclaimed it to be a success, thus clearing the way for the Japanese Second Army to land in Manchuria. Although Port Arthur was as good as blocked, due to the lack of initiative by Makarov's successors, Japanese naval losses began to mount, largely due to Russian mines. On 15 May, two Japanese battleships, the 12,320-ton and the 15,300-ton , sank in a Russian minefield off Port Arthur after they both struck at least two mines each, eliminating one-third of Japan's battleship force, the worst day for the Japanese Navy during the war.