Both ships, "Amur" and "Yenisei", were built by the Baltic Works in Saint Petersburg. They were laid down in 1898 and completed the following year. They were assigned to the Pacific Fleet when the Russo-Japanese War began in 1904 and based in Port Arthur. Two days after the Japanese surprise attack on Port Arthur on 8/9 February 1904, "Yenisei" was laying a minefield at Dalian Bay when one mine broke loose and began floating towards the ship. While maneuvering to avoid the mine "Yenisei" accidentally entered the minefield that she'd just laid and hit a mine. The consequent explosion caused eight mines still on the rails to detonate, killing 96 or 100 crewmen and sinking the ship in 20 minutes. The protected cruiser and four destroyers responded to the incident, but "Boyarin" hit one of "Yenisei"s mines. The explosion flooded the ship's machinery spaces and her crew abandoned ship. The cruiser remained afloat, but foundered in Dalian Bay the next day during a storm.