(1806) Military engagement of the Napoleonic Wars , fought between French troops and Prussians and Saxons.
In 1806 Frederick William III of Prussia signed a secret alliance with Russia and joined the Third Coalition against Napoleon . As the Prussian army moved through Saxony to meet its Russian allies, it was forced to face a French attack from the rear. The Prussians split their forces between Auerstedt and Jena, and on October 14 Napoleon swept the Prussian troops off the field at Jena. At the same time, a secondary French force under Louis Davout defeated a Prussian army more than twice its size at Auerstedt. Napoleon completed his conquest of Prussia in six weeks.