Demarcation line between Poland and Soviet Russia.
The British foreign secretary, Lord Curzon , proposed it as a possible armistice line in the Russo-Polish War of 1919–20. His plan was not accepted, and the final peace treaty (1921) provided Poland with almost 52,000 sq mi (135,000 sq km) of land east of the line. With the outbreak of World War II, the Soviet Union revived the line, claiming all the territory east of it. In 1945 a Soviet-Polish treaty officially designated a line almost identical to the Curzon Line as their mutual border.