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20 September in military history: the Battle of the Niemen, 1920

Military history · 20 September · Polish-Soviet WarFull calendar

Aerial view of a river with a collapsed iron truss bridge on stone piers, burned wooden bridges and floating debris, at the Battle of the Niemen, 1920
Wrecked bridges on the Niemen, photographed from a Polish aircraft in 1920 (date and source as given in the image's Wikimedia Commons record). Public domain, via Wikimedia Commons.
Quick answer

On 20 September 1920 Polish troops opened the Battle of the Niemen. A month after his defeat at Warsaw, Mikhail Tukhachevsky had pulled his Western Front back behind the Niemen and the Szczara and was preparing a new offensive toward Białystok and Brest. The Polish Commander-in-Chief, Józef Piłsudski, struck first. While the 2nd Army fought its way toward Grodno, a strike group swung north through Lithuanian-held territory and over the Niemen toward Lida, deep in the Soviet rear. Grodno fell on 25 or 26 September, depending on the source, and Lida soon after. The Red Army fell back east, and a ceasefire followed in October.

Battle of the Niemen, 1920: the final blow of the war

20 to about 28 September 1920 · 106 years ago

The Polish 2nd and 4th Armies under Józef Piłsudski broke Mikhail Tukhachevsky's new Soviet front on the Niemen. A northern hook through Druskieniki outflanked Grodno, the Red Army fell back, and an armistice followed on 12 October.

Read the full story of Battle of the Niemen, 1920: the final blow of the war ›

Battle of Valmy, 1792: the cannonade that saved the French Republic

20 September 1792 · 234 years ago

Near Valmy in Champagne, French troops under Kellermann and Dumouriez stopped the Duke of Brunswick's Prussian army on its march to Paris early in the French Revolutionary Wars. The small but unexpected victory saved the Revolution, and the monarchy was abolished soon after.

Read the full story of Battle of Valmy, 1792: the cannonade that saved the French Republic ›

Battle of the Alma, 1854: the first clash of the Crimean War

20 September 1854 · 172 years ago

Britain and France beat Menshikov's Russians at the Alma on 20 September 1854, the first major battle of the Crimean War. The armies, the losses and a map.

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Frequently asked questions

Who won the Battle of the Niemen?

Poland. According to Maciej Krotofil of the IPN, the battle threw the Soviet forces back about 100 km to the east, and two of the Western Front's four armies practically ceased to exist.

When was the Battle of the Niemen?

It began on 20 September 1920. Sources date its end differently: 28 September (Krotofil, Stawecki), 29 September (Wojciechowski) or 26 September (an IPN exhibition page), while Kutrzeba's 1926 study has it last almost without a break until the ceasefire of 18 October.

When did Poland take Grodno?

Krotofil writes that the first Polish patrols reached the city on the evening of 25 September. A brigade telegram reported Grodno taken at 0.45 in the night of 25 to 26 September, and the General Staff announced its capture in its communiqué of 26 September.

Who commanded the Polish armies?

Piłsudski, whose order of 19 September had the 2nd and 4th Armies strike under his personal command. The 2nd Army was led by Gen. Edward Rydz-Śmigły and the 4th by Gen. Leonard Skierski.

How did the Polish-Soviet War end?

A preliminary peace and armistice were signed in Riga on 12 October 1920, and the ceasefire took effect on 18 October.

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