The Battle of Eylau or Battle of Preussisch-Eylau, February 7 and 8, 1807, is a bloody and inconclusive battle between Napoleon's Grande Armée and the Imperial Russian Army under the command of Levin August, Count von Bennigsen near the town of Preussisch Eylau in East Prussia.

Late in the battle, the Russians receive a timely reinforcement from a Prussian division of von L'Estocq.

The town is now called Bagrationovsk and is a part of Kaliningrad Oblast, Russia.

The engagement is fought during the War of the Fourth Coalition, part of the Napoleonic Wars.

Napoleon's armies had previously smashed the army of the Austrian Empire in the Ulm Campaign and the combined Austrian and Russian armies at the Battle of Austerlitz on December 2, 1805.

On October 14, 1806, Napoleon had crushed the armies of the Kingdom of Prussia at the Battle of Jena-Auerstedt and hunted down the scattered Prussians at Prenzlau, Lübeck, Erfurt, Pasewalk, Stettin, Magdeburg and Hamelin.

In late January, Bennigsen's Russian army had gone on the offensive in East Prussia, pushing far to the west.

Napoleon had reacted by mounting a counteroffensive to the north, hoping to prevent their retreat to the east.

After his Cossacks captured a copy of Napoleon's orders, Bennigsen had rapidly withdrawn to the northeast to avoid being cut off.

The French had pursued for several days and found the Russians drawn up for battle at Eylau.

In a vicious evening clash, the French capture the village with heavy losses on both sides.

The following day brings even more serious fighting.

Early in the battle, a frontal attack by Napoleon failswith catastrophic losses.

To retrieve the situation, the emperor launches a massed cavalry charge against the Russians.

This buys enough time for the French right wing to throw its weight into the contest.

Soon, the Russian left wing is bent back at an acute angle and Bennigsen's army is in danger of collapse.

A Prussian corps belatedly arrives and saves the day by pushing back the French right wing.

As darkness falls, a French corps tardily appears on the French left flank.

That night Bennigsen decides to retreat, leaving Napoleon in possession of a snowy battlefield covered with thousands of corpses and many more wounded.

Eylau is the first serious check to the Grande Armée and the myth of Napoleon's invincibility is badly shaken.

The French will go on to win the war by decisively defeating the Russians on June14  at the Battle of Friedland.