(1905) Peace settlement that ended the Russo-Japanese War .
It was mediated by Pres. Theodore Roosevelt and signed at the U.S. naval base near Portsmouth, N.H. By its terms, Russia recognized Japan as the dominant power in Korea and ceded its leases to Port Arthur (now Lüshun) and the Liaodong Peninsula, as well as the southern half of Sakhalin, to Japan. Both powers agreed to restore Manchuria to China.