HistoryData
Historical ConflictWarsaw

Battle of Nasielsk

Sikorski's offensive at Nasielsk disrupted the Soviet right wing, enabling Piłsudski's decisive counter-offensive that saved Warsaw in August 1920.

Duration & Scope

1920 ongoing

< 1 year

Key Facts

Dates
14–15 August 1920
Polish force (5th Army)
3 infantry and 2 cavalry divisions
Soviet opposition
12 infantry and 2 cavalry divisions (3 armies)
Rivers crossed
Wkra and Vistula Rivers
Key intelligence capture
Soviet IV Army's plans and cyphers seized at Ciechanów

Strategic Narrative Overview

On the morning of 14 August 1920, Sikorski's forces crossed the Wkra and Vistula Rivers, taking the offensive against the Soviet right flank. General Karnicki raided Ciechanów, capturing the Soviet IV Army's operational plans and cyphers. By 16 August, Sikorski entered Nasielsk with tanks, armoured cars, and two armoured trains, and by 18 August had advanced to the Orzyc and Narew Rivers, keeping Soviet forces off balance.

01 / The Origins

In August 1920, Soviet forces advanced deep into Polish territory and besieged Warsaw, threatening the newly independent Polish state. Polish commanders planned a counter-offensive to relieve pressure on the capital. General Władysław Sikorski's Fifth Army was tasked with containing the Soviet right wing, composed of the 4th, 15th, and 3rd Armies, while Piłsudski prepared a decisive strike from the south along the Wieprz River.

03 / The Outcome

Sikorski's offensive cleared the Vistula bridgehead and enabled Piłsudski to launch his counter-strike on 16 August. The Soviets withdrew their 15th and 3rd Armies and abandoned the 4th Army, which was encircled and destroyed. The broader engagement, known as the Battle of Warsaw, ended in a major Polish victory that halted the Soviet westward advance and secured Poland's independence.

Belligerents & Mobilization Analysis

Side A

1 belligerent

Soviet Russia (4th, 15th, and 3rd Armies)

Side B

1 belligerent

Poland (Fifth Army)
Key Commanders

Władysław Sikorski, Gen. Karnicki.

Outcome
Polish victory; Soviet right wing disrupted; 4th Army abandoned and encircled; Warsaw counter-offensive enabled

Kinetic Engagement Axis

Major engagements timeline (1920–present)Timeline of major military engagements plotted chronologically.1920present1920Raid on CiechanówSide B1920Crossing of the …Side B1920Advance to Orzyc…Side B

Scroll horizontally to view full axis. Events plotted relatively.

Side A victorySide B victoryInconclusiveDecisive / turning point

Location

Map of Nasielsk, PolandMap of Nasielsk, PolandNasielsk, Poland