For future reference, this question is a good candidate for the Short Answers to Simple Questions thread.

That aside, the Polish lancers in the guard were not the only Polish light horse in Napoleon's army. Especially in his latter campaigns in Russia and Germany, Napoleon relied heavily on Polish contingents, alongside Germans and Italians, to match the armies of the enemy coalitions in the face of constant losses. The Duchy of Warsaw was a satellite state of France, carved out of the Polish territories of Prussia and Austria, and as such it was obligated to furnish troops for Napoleon's campaigns. During the invasion of Russia, these troops numbered more than 100,000, and were indeed the first casualties in the campaign, with several drowning during the crossing of the Nieman river.

Most Polish troops served in 5th Corps under Poniatowski, but most of the lancers fought as part of 4th Cavalry Corps in the uhlan regiments; the light cavalry division of Poniatowski's corps was mostly chasseurs. In the 1813 campaign in Germany, the army was reorganized, with the Poles forming the bulk of 7th Corps; they had a small advance guard, consisting of a cuirassier regiment and the krakus light horse, mounted on very small ponies and armed with lances. The Uhlans were once again allotted to the army reserves; this time under Kellerman, where they fought at Leipzig.