The combat of Zirke (11-12 February 1813) was one of the first clashes during the War of Liberation, and came during the French retreat from the Vistula to the Oder.
Prince Eugène de Beauharnais, Napoleon's step son, had been given the task of defending the French position in Eastern Europe, but he was in a very dangerous position. The Russians were slowly advanced west into Poland and East Prussia, while the officially neutral Prussians were clearly preparing to join the Coalition against France. As a result Eugène decided to abandon his positions around Posen and retreat to Frankfurt on the Oder.
The Bavarian Division of Eugène's army was based at Gnessen. It was given orders to retreat back to Posen as part of the move west. Two regiments of the Lithuanian Lancers were posted at Zirke (modern Sierakow, on the Warta west of Posen), where on the night of 11-12 February they were attacked by a force of Cossakcs.
The Lancers weren't strong enough to stand up to the Cossack force and suffered a heavy defeat. Both regiments were captured almost intact, including their commander, Prince Gedroitze.
Prince Eugène left Posen on 12 February with 9,000 men, and reached Frankfurt on 18 February. The Russians weren't quite a close as he believed, and the Russian advance guard, under Mikhail Semenovich Woronsoff, didn't reach Posen until 16 February.