Curzon Line

The line drew on a declaration of the Allied Supreme Council of 8 December 1919 on Poland's provisional frontier. During the Polish–Soviet War the British Foreign Secretary, Lord George Curzon, proposed it in a note to Moscow as an armistice line: from Grodno through Brest, along the Bug and east of Przemyśl to the Carpathians. Its real author was the Foreign Office official Lewis Namier, and in Galicia there were two variants, only one of which left Lwów on the Polish side. After Poland's victory in 1920 the Peace of Riga drew the frontier much further east.

In the Second World War Stalin demanded a border on the Curzon Line. At Tehran Churchill and Roosevelt agreed to it in principle without telling the Polish government, and at Yalta the three powers adopted it as the basis of the frontier. The Polish–Soviet agreement of 16 August 1945, with small deviations, left Wilno and Lwów in the USSR.