Karafuto Prefecture
After the Russo-Japanese War, when the strategic importance of control of the Tsugaru Straits came into focus, and with Japan's acquisition of Karafuto Prefecture, more investment was made in securing Japan's northern frontiers. Ōminato was one of eleven designated third echelon naval ports, or located in various locations around Japan. In December 1905 it was made independent of Yokosuka. Although Muroran, Asahikawa and Wakkanai bases reported to Ōminato, it was not raised to full headquarters status, but continued as Ōminato "yokobu". A wireless station was completed in 1913.