The initial expedition, in which 65,000 Polish and 15,000 Ukrainian soldiers took part, started on 24 April 1920. The military goal was to outflank the Soviet forces and destroy them in a single battle. After winning the battle in the South, the Polish General Staff planned a speedy withdrawal of the Polish 3rd Army and strengthening of the northern front, where Piłsudski expected the main battle with the Red Army to take place. The Polish southern flank was to be held by Polish-allied Ukrainian forces under a friendly government of Ukraine. On 7 May, Polish and Ukrainian soldiers entered Kiev.