During 1919, with the exception of the short period of hopes for the world revolution that came to life at the beginning of the year, was secondary in comparison with the Eastern, Southern and Northwestern fronts, where the fate of the Soviet system was decided. The defeats of Kolchak, Denikin and Yudenich raised the importance of the front. The success of the Polish troops in 1919 also contributed to this. Having abandoned the alliance with the white movement, Poland, led by J. Piłsudski, was successively strengthened by military means in disputed territories. The first unsuccessful actions near Vilnius in early 1919 were soon replaced by a succession of victories. In early March, Polish troops occupied Slonim and Pinsk, and on April 21, after three days of fighting, Vilnius, where a Jewish pogrom was organized to occupy the city. By August 1919, Polish forces already controlled the entire territory of Belarus.

The further offensive of the Polish troops was halted due to the victories of Denikin, whose successful actions did not meet the interests of Poland. Attempts of Yu. Pilsudski to propose Poland to En-Tante as the main anti-Bolshevik force at that time were unsuccessful due to the Allies' stakes on Denikin. Under these conditions, Poland participates in negotiations with Russia, while simultaneously mobilizing new units for military operations in the East.

The defeat of the white armies, the rate of the Entente on Poland as the only real military force in the region, the completed mobilization of troops led to the termination of negotiations in December 1919. In January-March-March 1920, Poland rejected the Soviet peace proposals and on March 5, 1920 undertook in the offensive of Mozyr and Kalinkovichi. The failure of the military operation only accelerated the preparation of a large-scale expansion into Ukraine. On April 21, J. Pilsudski signed a treaty of alliance with S. V. Petliura, and on April 24, a military convention providing for the armed assistance of the Polish army in the restoration of Petliura's power in Ukraine.

Signed documents gave Poland water to invade Soviet Ukraine. In addition to the establishment of the Petliura regime in Ukraine, the outbreak of the war was to consolidate Poland’s control over the Belarusian lands and a number of other disputed territories. The Belarusian statehood was not envisaged, and for the help of Pet l Jure Poland secured Eastern Galicia and five counties of the Volyn province. The Entente, which supported Poland, had its own interests in the war. The most significant assistance was to France, which provided a loan in the amount of over 1 billion francs and transferred 1494 ordiums, 350 aircraft, 2,800 machine guns, 327,5 thousand rifles, 42 thousand re-volvers, etc. to Poland in early 1920s. .

On April 25, 1920, a well-equipped 150-thousand Polish army broke through the 50-thousand South-Western front from the Pripyat River to the Dniester River. As a result of a large-scale offensive, a day after its start, Zhytomyr and Korosten were captured, and on May 6-7, Kiev. The military successes, however, were relative, since the absence of major battles did not allow the Poles to defeat the main enemy forces in Ukraine, and the calculations for restoring the Petliura administration did not materialize, turning into widespread spontaneous uprisings. Large losses, stretched communications and consumed reserves complemented the picture. In mid-May, the front stabilized.

The Soviet side was defending, which provided a moral advantage at this stage of the war. The Polish offensive touched national feelings, and a significant part of the Russian officers, at the call of General A. A. Brusilov, joined the ranks of the Red Army. The combination of public impulses and government measures allowed the Red Army to strengthen its forces on the West (M.N. Tukhachevsky) and South-West (A.I. Egorov) fronts of the cage of 1920.

After the first unsuccessful May counterattack, on June 5, the 1st Cavalry Army of S. M. Budyonno broke through the front, going to the rear of the Polish units occupying Kiev. Avoiding complete encirclement, the Polish units were forced on June 12 to retreat from Kiev. The offensive of the South-Western Front in Ukraine continued, and on July 4, units of the 1st Cavalry Army liberated Rivne. In parallel, in July, the offensive units of the Western Front began to develop successfully, on July 4 and 5, the Polish forces breaking into the defenses. The offensive on the Western Front was facilitated by the transfer of Polish units to the South-Western Front. On July 11, Division B, K. Putny liberated Minsk, and on July 14, G. D. Guy's cavalry corps occupied Vilnius, on July 19, Western Front troops occupied Baranavichy and Grodno, July 23 - Pinsk, July 25 - Volkovysk, freeing the entire territory of Belarus,

By the end of July, parts of the Red Army had already moved military operations to Poland. The starting point was the directive of Commander-in-Chief S. S. Kamenev of July 23, 1920, about the attack on Warsaw and Lviv. For military plans were political directives, which consisted in an attempt to revolutionize Poland, and later on Europe.

An important role in the Sovietization of Poland was to be played by the Provisional Revolutionary Committee of Poland formed on July 30 in Bialystok under the leadership of K.Kh. Markhlevsky. However, the policy of the Revolutionary Command Committee rather caused rejection of the Polish population than support. The hasty replacement of voivodships in the regions, the nationalization of lands, anti-Catholic actions, and the support of Soviet troops of the Revolutionary Command Army formed the anti-national image of the new government. Now the Soviet troops had to deal with the partisan movement.

On July 23, 1920, the Warsaw operation began, which coincided with the military difficulties of the Soviet army at the front of P. N. Wrangel, who launched an offensive in Northern Tavria in the summer. By the beginning of the operation, parts of the Western Front were located 80–100 km from Warsaw. Under these conditions, on August 5, the Ple-Num of the Central Committee of the RCP (B.) Approved the decision to transfer the 1st Cavalry, the 12th and the 14th armies of the South-Western Front at the disposal of Tukhachevsky. The gap of the South-Western Front is in fact divided into three parts (Lviv and Crimean directions and the parts allocated to Tukhachevsky) weakened the offensive on the southern flank of the Soviet troops. In addition, the transfer of troops was belated, both because of the deadlines that were insufficient to implement the decisions, and because of the delayed transfer of disputes between the command of the South-Western and Western Fronts.

The reluctance of Egorov and Stalin (a member of the Revolutionary Military Council of the South-Western Front) to give their shock units extremely complicated the movement of troops. To solve the high political tasks assigned to the Western Front, had limited military means. The situation was aggravated by the mistake made by Tukhachevsky in assessing the location of the main Polish units not at the point of his strike, but on the flank south-east of Warsaw. The isolation of troops from rear supply and even front command, as well as the overwhelming superiority of the Polish troops near Warsaw, also played a disastrous role.

The strike of August 19 on the flank of the advancing units of the Western Front by Polish troops, under the command of French General M. Weygen, turned the near victory into an unconditional defeat. The Miracle on the Vistula was the result of the military and political failures of the Soviet leadership and the collapse of the plan of the world revolution, "unexpectedly" stumbled upon the resistance of the Poles. Leonid Trotsky described the situation very precisely: “When we were close to Warsaw in a somnambulistic state, where there was no revolutionary upsurge, but a fist was created, a counter-revolutionary led by the French, he hit us neatly and deftly, and it turned out to be one of the greatest catastrophes we ever experienced on our military fronts. " A significant part of the troops of the Western Front was in the environment. About 130 thousand Red Army soldiers were in Polish captivity, of which 60 thousand died in two years in concentration camps for prisoners of war.

The mutual exhaustion of armies, the political hopelessness of further military actions were visible to both countries. Under these conditions, on October 18, 1920, hostilities ceased. The truce, and later the Riga Peace Treaty (March 18, 1921), fixed the border pushed to the west by 50-100 km compared to the beginning of 1920. For Poland, however, the lands of Western Ukraine and Western Belarus were consolidated, and 30 million gold rubles were paid to it for a year.

The end of hostilities in Poland allowed the Red Army to concentrate the main forces against the forces of P. N. Wrangel. Already in September 1920, Soviet troops outnumbered the enemy in the infantry and in the total number of troops. On September 21, 1920, the Southern Front was formed (commander M. V. Frunze, members of the Revolutionary Military Council S. I. Gusev, Bela Kun). Preparations for a general offensive were carried out under conditions when the enemy launched a new offensive on the Donbass. Wrangel's troops captured Aleksandrov, Mariupol, but they could not break through to the Donbass. On October 8, the troops of P. N. Wrangel attempted to transfer military operations to Right-Bank Ukraine, setting up battles for Kakhovka, where they were opposed by units of V. K. Blucher. After repulsing the tank attacks of the enemy, the Soviet units on October 15 launched a counteroffensive, winning a convincing victory.

The exhaustion of the last reserves of P. N. Wrangel in the autumn battles was complemented by the increasing advantage of Soviet troops reinforced by units arriving from Poland. By the beginning of the decisive counteroffensive on October 16, 1920, the units of the Red Army surpassed the enemy in infantry by more than four times, and by cavalry — almost three times. As a result, Wrangel's army in Northern Tavria suffered a severe defeat: only about 20 thousand people were captured. The task now was to liberate the Crimea with its powerful defensive lines on the Perekop and Chongarsky trans-rakes.

The Perekopsky Isthmus was especially strongly fortified, where the main line of defense passed along the Turkish shaft 8 m high, and in front of the shaft there was a ditch up to 20 m wide and 10 m deep, as well as three-row wire barriers. The approaches were guarded with the help of 70 guns and 150 bullets. South of the village of Yushun a reserve, also heavily fortified, second line of defense passed.

The assault on the Crimean fortifications began on November 7, 1920 simultaneously from two sides: from the front, head to the Perekop positions (parts of V. K. Blucher and the Makhnovist detachments) and to the flank of the Wrangel Ukr-Pleniyam through Sivash. On November 9, 1920, the Soviet forces from the fourth attempt took the Turkish rampart, while a great role was played by the diversion of the Wrangel reserves to the Lithuanian peninsula, which, after crossing the Sivash on November 8, was captured by Soviet units. Attempts to organize resistance to the advancing troops of the Red Army on the Yushun positions were unsuccessful due to the Soviet forces breaking through the defensive lines on the Chongar isthmus on November 11 and leaving them to the rear of the enemy.

On November 13, units of the 1st Cavalry Army liberated Simferopol, and on November 15, Sevastopol, by the 20th, the entire Crimea became Soviet. The total number of dead and wounded during the storming of the isthmuses was not less than 10 thousand people. The fierce resistance of the Wrangel troops provoked a response. After the liberation of the Crimea, 8 to 12 thousand people belonged to the defeated side were shot. The majority of the Wrangel troops and their families in the amount of 145,693 people were evacuated on 126 ships shortly before. The last ship, the battleship Kornilov, left Sevastopol on November 14 at 18 o'clock. On board was the commander-in-chief of the white movement, P.N. Wrangel.