During the Napoleonic Wars, the Duchy of Warsaw raised uhlan formations. Polish lancers serving with the French Army included the Legion of the Vistula and the 1st Polish Light Cavalry Regiment of the Imperial Guard. The Imperial Guard lancers were armed with Lances, Sabres and Pistols. The lancers of the Polish expeditionary corps, which fought alongside the French in Spain and Germany, spread the popularity of the Polish model of light cavalry. After the Battle of Somosierra, Napoleon said that one Polish cavalryman was worth 10 French soldiers. The chevaux-légers, French light cavalry units from the 16th century till 1815, were remodelled after the Uhlans. Following the Treaty of Tilsit in 1807, lancer regiments designated as Uhlans were reintroduced in the Prussian service. Initially, they were only three. After the War of the Sixth Coalition, Uhlan regiments were formed from Lützow Free Corps, Schill Free Corps, Bremen Volunteers and Hellwig's Streifkorps.