Most famously , on May 15 , 1904 , the Russian minelayer Amur planted a 50 - mine minefield off Port Arthur .
Most famously , on May 15 , 1904 , the Russian minelayer Amur succeeded in sinking the Japanese battleships Hatsuse and Yashima .
Most famously , on May 15 , 1904 , the Russian minelayer Amur planted a 50 - mine minefield off Port Arthur and succeeded in sinking the Japanese battleships Hatsuse and Yashima .