The combat of Kalisch (18 February 1813) was one of the first clashes of the War of Liberation of 1813 and played a part in forcing the French to abandon any attempt to defend eastern Germany.
Overall command of the weak French forces in Poland and eastern Germany had been given to Prince Eugène de Beauharnais. He had a handful of troops to defend a massive front line, and suffered from interference from Napoleon, who repeated issued unrealistic orders.
In mid February Eugène was forced to retreat towards the Oder. Reynier's VII Corps, Schwarzenberg's Austrian contingent and Prince Poniatowski's Poles made up his right flank, but this force was dramatically weakened when Schwarzenberg retreated into Galicia, taking Poniatowski's 8,000-9,000 Poles with him, before signing an armistice. Poniatowski had no choice other than to accept this armistice, leaving Reynier to fight alone.
Reynier paused around Kalisch (modern Kalisz, some way to the east of the Oder), with the survivors of VII Corps. He was being pursued by General Wintzingerode, who had two infantry divisions and 6,000 cavalry (including a detachment under General Davydov), a much larger force.
Wintzingerode crossed the Vistula at Plock, and advanced south-west. He crossed the Wartha and Kolo, and then continued south-west towards Reynier. On 18 February he launched an attack on Reynier. The attack was so violent that the individual French regiments were unable to concentrate at their agreed reindezvous at Kalisch, and instead had to concentrate on making individual breakthoughs to escape. Despite this Reynier was able to organise a defence that lasted until the evening. He then withdrew to Glogau on the Oder. The attempt to defend the Oder didn't last for much longer, and Eugène was soon forced to retreat west towards the Elbe.
Not all of Reynier's units were able to escape. The Saxan General Nostiz, with 500 men and four guns, was forced to surrender. After this clash Reynier had 9,000 men under his command.