The frontiers between Poland, which had established an independent government after World War I, and the former Russian Empire were not recognized by the League of Nations. Poland's Józef Piłsudski, who envisioned the formation of an Intermarium federation as a Central and East European bloc that would be a bulwark against Germany to the west and Russia to the east, carried out a Kiev Offensive into Ukraine in 1920. This met with a Red Army counter-offensive that drove into Polish territory almost to Warsaw, Minsk itself was re-captured by the Soviet Red Army on 11 July 1920 and a new Byelorussian Soviet Socialist Republic was declared on 31 July 1920. Piłsudski, however, halted the Soviet advance at the Battle of Warsaw and resumed his eastward offensive. Finally the Treaty of Riga, ending the Polish–Soviet War, divided Belarus between Poland and Soviet Russia. Over the next two years, the People's Republic of Belarus prepared a national uprising, ceasing the preparations only when the League of Nations recognized the Soviet Union's western borders on 15 March 1923. The Soviets terrorised Western Belarus, the most radical case being Soviet raid on Stołpce. Poland created Border Protection Corps in 1924.