Which battle in 1807 was the first major clash between French and Russian armies?

The Battle of Eylau was the first major clash between French and Russian armies in the 1807 campaign. Fought on 7–8 February 1807 near Preussisch Eylau in East Prussia, it brought Napoleon's Grande Armée into a brutal confrontation with Russian forces commanded by General Levin August von Bennigsen, supported by a Prussian corps.

The battle followed earlier engagements at Czarnowo, Pultusk, and Golymin, but Eylau was the first full-scale, strategically important meeting between Napoleon's main army and the Russians. Snowstorms, intense artillery fire, and a large French cavalry charge led by Marshal Murat made the fighting exceptionally costly.

Unlike Napoleon's more decisive victories at Austerlitz and Friedland, Eylau was strategically inconclusive. Both armies claimed success, but neither destroyed the other, and the French advance was halted. The battle's heavy casualties shocked contemporaries and exposed the increasingly attritional character of the Napoleonic Wars.

Friedland, fought in June 1807, was the later and more decisive French victory that helped lead to the Treaties of Tilsit.