The Lancers

During the Napoleonic Wars many nations fielded horsemen armed with a lance. These were mainly lightcavalry as in French, Austrian and Prussian service. The lance allowed the light horsemen to hit hard during the initial attack and use the weapons greater reach to poke at infantry in 'square' formation (although with limited success). Lancers (also known as Uhlans in Prussian and Austrian service) often adopted Polish style dress with the distinctive 'Czapka' cap, as most countries had modeled their Lancer Regiments on those of the Poles. Only the British army was without Lancers during the Napoleonic wars and this was to prove costly when the French used their lancers to good effect during the battle of Waterloo, The British learned from this and by the Crimean war the British army also had lancers. The Russian army had both lancers in the traditional Polish style uniforms and large numbers of irregular light horsemen, the 'Cossacks' who frequently carried a lance along with a variety of other weapons.

http://www.historyofwar.org/articles/weapons_lancers.html