HistoryData
war1920

Conflict between Poland and Soviet Russia following the First World War (February 1919 - March 1921)

October 18, 1920

The Polish–Soviet War halted the westward spread of Bolshevism into Europe and established Poland's eastern borders through the 1921 Peace of Riga.

Quick Facts

Year
1920
Category
war

Key Facts

War duration
14 February 1919 – 18 March 1921
Ceasefire date
18 October 1920
Peace treaty
Peace of Riga, signed 18 March 1921
Polish border gain
Approx. 200 km east of the Curzon Line
Battle of Warsaw
12–25 August 1920, known as 'Miracle on the Vistula'
Kiev captured by Poland
7 May 1920

By the Numbers

14
War duration
18
Ceasefire date
18
Peace treaty
200
Polish border gain

Location

Map of PolandMap of PolandPoland

Cause → Event → Consequence

Cause

After the collapse of the Central Powers in 1918, Soviet Russia annulled the Treaty of Brest-Litovsk and moved forces westward to reclaim former territories. Lenin viewed independent Poland as a corridor for spreading communist revolution into Western Europe, while Polish leader Józef Piłsudski sought to restore Poland's pre-1772 borders and establish a broad federation to counter Soviet power.

Event

Polish forces occupied much of Lithuania and Belarus in 1919 before Piłsudski launched the Kiev offensive in April 1920, briefly capturing the city. A Soviet counteroffensive pushed Polish forces back to Warsaw by August, but the Battle of Warsaw (12–25 August 1920) ended in a decisive Polish victory. A ceasefire was declared on 18 October 1920, followed by the Peace of Riga on 18 March 1921.

Consequence

The Peace of Riga divided disputed territories, establishing Poland's eastern border roughly 200 km east of the Curzon Line and securing Polish control over parts of modern Ukraine and Belarus. The war also resulted in formal Soviet recognition of the Ukrainian and Byelorussian Soviet Socialist Republics, undermining Piłsudski's Intermarium federation plans while confirming Poland's role in Eastern European geopolitics.

Belligerents & Mobilization Analysis

Side A

2 belligerents

Second Polish RepublicUkrainian People's Republic
Key Commanders

Józef Piłsudski, Symon Petliura.

Side B

1 belligerent

Russian Soviet Federative Socialist Republic
Key Commanders

Vladimir Lenin.

Outcome
Polish victory; Peace of Riga signed 18 March 1921, establishing Poland's eastern border approximately 200 km east of the Curzon Line.

Timeline Context

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