The war with the Bolshevists dragged on through the winter of 1919–20, largely because the Entente Powers felt that it might be possible to use Poland against Russia in conjunction with the Kolchak and Denikin movements. The Poles launched an offensive at the end of April, 1920, and within two weeks had advanced to Kiev. But the Bolshevists, having disposed of counter-revolutionary movements, were able to concentrate all their forces against Poland. There was a sudden change in the fortune of arms. Poland was invaded, and by the middle of August the Russians had advanced to the suburbs of Warsaw. In the meantime the Poles had sued for an armistice. Polish plenipotentiaries went to Minsk on August 17, prepared to accept humiliating terms, which included the reduction of the Polish army to fifty thousand, the surrender of all arms and war materials over and above what was necessary for this small army, and the stoppage of war industries. These terms, together with the proposal for the Vistula boundary, had been transmitted to Poland by the intermediary of the British, and seemed reasonable to the British Government, which had never countenanced Poland’s inordinate territorial ambitions. By the time the Polish peace delegation reached Minsk, the tide of battle had begun to turn. With French staff aid the Polish army made a successful counter-offensive, and the Bolshevists retreated as rapidly as they had advanced. The shoe being now on the other foot, negotiations were transferred to Riga, where on October 12, 1920, a treaty was signed as humiliating to Russia as the one the Bolshevists had intended to make the Poles accept. Ukrainia was associated with Russia in making the peace. Poland tried to avoid dealing with Ukrainia as a Soviet government, but on this point Moscow and Kiev were obdurate. It was a surprise to the world that the Moscow Soviet agreed to cede one hundred and thirty-five thousand square kilometers, which meant the loss of part of White Russia and the cutting off of Russia from Lithuania. Poland secured a corridor to Latvia, which enabled her to begin immediately a frontier dispute with that little state. Russia renounced intervention in negotiations between Lithuania and Poland, which left Lithuania at the mercy of her larger neighbor. The cessions in the northwest, when taken into consideration with the creation of the Baltic Republics, made still more difficult the trade communication of Russia with Germany and the rest of western Europe. In the south Poland established a common frontier with Rumania at a sacrifice on the part of Soviet Ukrainia both of a large part of Volhynia province, with a purely Ukrainian population of more than a million, and also of the claim to a union with Eastern Galicia, with three million more Ukrainians.