The Battle of Warsaw (; , ), also known as the Miracle on the Vistula (), was a series of battles that resulted in a decisive Polish victory and complete disintegration of the Red Army in August 1920 during the Polish–Soviet War.

After the Polish Kiev offensive, Soviet forces launched a successful counterattack in summer 1920, forcing the Polish army to retreat westward. The Polish forces seemed on the verge of disintegration and observers predicted a decisive Soviet victory.

The Battle of Warsaw was fought from August 1920, as Red Army forces commanded by Mikhail Tukhachevsky approached the Polish capital of Warsaw and the nearby Modlin Fortress. On August 16, Polish forces commanded by Józef Piłsudski counterattacked from the south, disrupting the enemy's offensive, forcing the Russian forces into a disorganized withdrawal eastward and behind the Neman River. Estimated Russian losses were 10,000 killed, 500 missing, 30,000 wounded and 66,000 taken prisoner, compared with Polish losses of some 4,500 killed, 10,000 missing and 22,000 wounded.

The defeat crippled the Red Army; Vladimir Lenin, the Bolshevik leader, called it "an enormous defeat" for his forces.Timothy Snyder (2007), Sketches from a Secret War, Yale University Press, p. 11 In the following months, several more Polish follow-up victories secured Poland's independence and led to a peace treaty with Soviet Russia and Soviet Ukraine later that year, securing the Polish state's eastern frontiers until 1939.

The politician and diplomat Edgar Vincent regards this event as one of the most important battles in history on his expanded list of most decisive battles, since the Polish victory over the Soviets halted the spread of communism further westwards into Europe. A Soviet victory, which would have led to the creation of a Soviet-established government in Poland, would have put the Soviets directly on the German border, where they were expecting or were promised aligned forces.

Prelude In the aftermath of World War I, Poland fought to preserve its newly regained independence, lost in the 1795 partitions of Poland, and to carve out the borders of a new multinational federation (Intermarium) from the territories of their former partitioners, Russia, Germany, and Austria.

At the same time in 1919, the Bolsheviks had gained the upper hand in the Russian Civil War, having dealt crippling blows to the Russian White Movement. Vladimir Lenin viewed Poland as a bridge to bring communism to Central and Western Europe, and the Polish–Soviet War seemed the perfect way to test the Red Army's strength. The Bolshevik's speeches asserted that the revolution was to be carried to western Europe on the bayonets of Russian soldats and that the shortest route to Berlin and Paris lay through Warsaw. The conflict began when Polish head of state Józef Piłsudski formed an alliance with the Ukrainian leader Symon Petlyura (on April 21, 1920) and their combined forces began to push into Ukraine, entering Kiev on May 7.

The two sides were embroiled in the Polish–Ukrainian War, amidst competing territorial claims. After early setbacks against Poland in 1919, the Red Army was overwhelmingly successful in a counter-offensive in early 1920 that nullified the Polish Kiev Operation, forcing a Polish retreat. By mid-1920, Poland's very survival was at stake and foreign observers expected it to collapse at any moment. The Russian strategy called for a mass push toward the Polish capital, Warsaw. Its capture would have had a major propaganda effect for the Russian Bolsheviks, who expected the fall of the Polish capital not only to undermine the morale of the Poles, but to spark an international series of communist uprisings and clear the way for the Red Army to join the German Revolution.

The Russian 1st Cavalry Army under Semyon Budyonny broke through Polish lines in early June. The effects of that were dramatic; Budyonny's success resulted in a collapse of all Polish fronts. On 4 July, Mikhail Tukhachevsky's Western Front began an all-out assault in Belarus from the Berezina River, forcing Polish forces to retreat. On 19 July the Red Army seized Grodno, on 22 July the Brześć Fortress was captured and on 28 July, it reached Białystok. In early August, Polish and Soviet delegations met at Baranavichy and exchanged notes, but their talks came to nothing.

Orders of battle

Polish

3 Fronts (Northern, Central, Southern), 7 Armies, a total of 32 divisions: 46,000 infantry; 2,000 cavalry; 730 machine guns; 192 artillery batteries; and several units of (mostly FT-17) tanks.

Polish army Northern Front Haller Central Front Rydz-Śmigły Southern Front Iwaszkiewicz 5th Army Sikorski 4th Army Skierski 6th Army Jędrzejewski 1st Army Latinik 3rd Army Zieliński 2nd Army Roja

Fronts: Northern Front: 250 km., from East Prussia, along the Vistula River, to Modlin: 5th Army 1st Army – Warsaw 2nd Army – Warsaw Central Front: 4th Army – between Dęblin and Kock 3rd Army – between south of Kock and Brody Southern Front – between Brody and the Dniester River

Soviet Red Army North-Western Front Tukhachevsky 4th Army Shuvayev 3rd Cavalry CorpsBzhishkyan 15th Army Kork 3rd ArmyLazarevich 16th ArmySollogub 1st Cavalry ArmyBudyonny

Battle plans Polish

By the beginning of August, the Polish retreat had become more organized, as their supply lines were steadily shortened. At first, Józef Piłsudski wanted to stop the Soviets at the Bug River and the city of Brest-Litovsk, but the Soviet advance resulted in their forces breaching that line, making that plan obsolete. On the night of August 5–6, Piłsudski, staying at the Belweder Palace in Warsaw, conceived a revised plan. In the first phase, it called for Polish forces to withdraw across the Vistula River and defend the bridgeheads at Warsaw and at the Wieprz River, a tributary of the Vistula southeast of Warsaw. A quarter of the available divisions would be concentrated to the south for a strategic counteroffensive. Next, Piłsudski's plan called for the 1st and 2nd Armies of General Józef Haller's Central Front ( divisions) to take a passive role, facing the Soviet main westward thrust and holding their entrenched positions, Warsaw's last line of defence, at all costs. At the same time, the 5th Army ( divisions) under General Władysław Sikorski, subordinate to Haller, would defend the northern area near the Modlin Fortress; when it became feasible they were to strike from behind Warsaw, thus cutting off Soviet forces attempting to envelop Warsaw from that direction, and break through the enemy front and fall upon the rear of the Soviet Northwestern Front. Additionally, five divisions of the 5th Army were to protect Warsaw from the north. General Franciszek Latinik's 1st Army would defend Warsaw itself, while General Bolesław Roja's 2nd Army was to hold the Vistula River line from Góra Kalwaria to Dęblin.

The crucial role, however, was assigned to the approximately 20,000-strong, newly formed Task Force (also translated as "Strike Group" or "Strike Army", from Polish ), under the personal command of Piłsudski. This unit, composed of the most elite Polish units from the southern front, was to be reinforced by General Leonard Skierski's 4th Army and General Zygmunt Zieliński's 3rd Army. After retreating from the Bug River area, those armies had not moved directly toward Warsaw but had crossed the Wieprz River and broken off contact with their pursuers, thus confusing the enemy as to their whereabouts. The Assault Group's assignment was to spearhead a rapid offensive from their southern position in the Vistula-Wieprz River triangle. They were supposed to advance north, targeting a weak spot that the Polish intelligence thought to have found in between the Soviet Western and Southwestern Fronts, where their communications relied on the weak Mozyr Group. The aim of this operation was to throw the Soviet Western Front into chaos and separate it from its reserves. According to the plan, Sikorski's 5th Army and the advancing Assault Group would meet near the East Prussian border, leaving the Soviets trapped in an encirclement.

Although based on fairly reliable information provided by Polish intelligence and intercepted Soviet radio communications, Ścieżyński, Mieczysław, Colonel of the (Polish) General Staff, [Radiotelegraphy as a Source of Intelligence on the Enemy], Przemyśl, Printing and Binding Establishment of (Military) Corps District No. X HQ, 1928. Paweł Wroński, [A Remarkable Discovery: There Was No Miracle at the Vistula], Gazeta Wyborcza. the plan was called 'amateurish' by many high-ranking army officers and military experts, from Polish officers to the advisors from the French Military Mission to Poland who were quick to point out Piłsudski's lack of formal military education.

Criticism was levied on the logistical side, as suggested concentration points were as far as from many Polish units, most of them engaged on the front lines, and all of that a mere week before the planned date of the counterattack. All regrouping was within striking distance of the enemy; if Piłsudski and his staff mistimed when the Soviet offensive would begin, the Polish counter-attack and even the cohesion of the entire Polish front would be in chaos. Piłsudski himself admitted in his memoirs that it was a gamble; he decided to go forward with it due to politicians' defeatist stance, fear for the safety of the capital, and the prevailing feeling that if Warsaw were to fall, all would be lost. Only the desperate situation persuaded other army commanders to go along with it. They realized that under the circumstances, it was the only possible way to avoid a devastating defeat. The plan seemed so desperate and inept, that when the Soviets intercepted a copy of it, it was discarded as a poor deception attempt.

The authorship of the plan is a matter of some controversy. Due to Piłsudski's political image, he was largely unpopular with the right wing of Polish politics. Furthermore, Paderewski told top Allied leaders that French general Maxime Weygand had the idea; Paderewski knew better, but he was trying to use American support for a comeback in Polish politics.Biskupski 1987 After the battle, many reports suggested that the plan was in fact prepared either by Weygand or by the Polish Chief of Staff Tadeusz Jordan-Rozwadowski. According to recent research, the French Military Mission proposed only a minor tactical counter-attack of two divisions towards Mińsk Mazowiecki. Its aim would have been to push the Red Army 30 kilometres back in order to ease subsequent ceasefire negotiations. On the other hand, General Rozwadowski's plan called for a deeper thrust into Russian lines from the area of Wieprz. However, Piłsudski proposed a large-scale operation, with significant forces committed to beating the enemy forces rather than merely pushing them back. The plan was opposed by the French mission, which did not believe that the Polish army would be able to regroup after a 600-kilometre retreat. Nonetheless, for many years, a myth persisted that it was the timely arrival of Allied forces that had saved Poland, a myth in which Weygand occupied the central role.

Davies points out Piłsudski "was left with only one serious possibility—a counter-offensive to the right of centre, at a point where a strike-force could be assembled from both northern and southern fronts. He pondered and checked these considerations during the night of 5–6 August, ruminating alone in his study at Belweder in Warsaw. In the morning, he received Rozwadowski and together they worked out the details. Rozwadowski pointed out the value of the River Wieprz ... by the evening, Order No. 8358/3 ... was ready and issued." Gen. Weygand admitted in his memoirs that "the victory was Polish, the plan Polish, the army Polish".. Davies, N. (1972), White Eagle, Red Star, London: Macdonald & Co,