The Battle of Eylau, or Battle of Preussisch-Eylau, was a bloody and strategically inconclusive battle on 7 and 8 February 1807 between Napoleon's Grande Armée and the Imperial Russian Army under the command of Levin August von Bennigsen near the town of Preussisch Eylau in East Prussia. Late in the battle, the Russians received timely reinforcements from a Prussian division of von L'Estocq. After 1945, the town was renamed Bagrationovsk as part of Kaliningrad Oblast, Russia. The engagement was fought during the War of the Fourth Coalition, part of the Napoleonic Wars.

Levin August Gottlieb Theophil, Graf von Bennigsen was a German general in the service of the Russian Empire. Bennigsen made a name for himself in Russian history as the man who fought Napoleon Bonaparte with distinction at the Battle of Eylau; but, suffering from ill-health, he was then defeated at Friedland several months later. Bennigsen also played a pivotal role in decisively defeating Napoleon in the War of the Sixth Coalition.