Ulans, where originally a Polish formation starting in the early 1700(1715 If I recall) It was an adaptation of traditional Polish Light cavalry from the 15-1600's with some of the inspiration going to another formation of the Polish army, Tartar Bosniaks. When the first Ulan formations where entering the Army Poland's king was also the elector of Saxony. It was the Saxons who used a few formations of Ulans in the War of Austrian Succesion and other wars where the did meat Prussian units. The Prussians attempted to make their own formations, but as said before converted them into Hussars. The Comte de Saxe also had a few formations of Ulans which is where the french first saw them. The Ulans where ment to take the place of Polands long since dwindiling Husaria formations, who at the time where scarce. The tactics for the Polish army was the striking arm, After bombardment from artillary a charge of Ulans was to take place, supported by other formations of Cavalry, this was because Poland's military did not like using traditional line infantry mainly because of the need to travel larger distances, with one army, since Polish congress was always suspecious of a king with a loyal and large standing army. The headgear, the Rogatiewka, was adopted by the Ulans in between the 2nd and 3rd Partitions, it was just the headgear(czapka means hat in Polish, which was eventualy called Chapka or Chapska in other European countries) it was the traditional hat of the Citizens who lived in Krakow, and at the time, a symbol of Koscuiszko's revolutionary ideas(I.E. All people are equal from the Nobles on hte horses to the peasents in the fields). The Ulans where the main fighting force in the Polish Insurection against the 3rd Partition. Tactics at that time generally followed Massive Bombardment with Cannons(Poland at the time had many more cannons than muskets, since cannon foundries where in the lands still held, Musket factories where usally in lands that where previously partitioned) after bombardment charge by the cav(Namely Ulans, and Hussars, or the occasional Dragoons), then a "Mop-Up" by the Scytheneers(Peasents armed with "war syths"). A few Battles where won this way, but eventually the superiour manpower of Russia and Prussia won threw and in 1795 Poland ceased to exist.
By Napolenic times Polish Ulans where easily recruited into Nappy's army since they wanted to liberate their homeland. Many where veterans of the war with Prussia and Russia, and many still fought with their older uniforms(later Frenchinized to one similar to the one given here). The lance was a potent weapon because it outreached Bayonetts, as well as the Sabers/broadswords carried by most other cavalry and on more than one occasion they ripped threw infantry fairly easily. As said before lancers where used until WW1 in their traditional roles. By the end of WW1 cavalry basicly became pretty much the same in all but name in most countries. From 1919-1920 the Polish Soviet War raged and both sides used alot of cavalry, armed with Cold steel simply because of lack of ammunition, but optimily the units where armed with Rifles, and other infantry weapons. By 1930 Polish Cavalry(Ulans, Mounted Rifles, and Light Horse where basicly all the same, except in name) stopped using the Lance as a battlefield weapon, and only used it for parades. Some did go in wagons with the cav when WW2 broke out and where used by the cavarly generally to good succes in the few charges that did take place(All the charges that did take place where also against infantry targets and never against tanks), but the prefered way to fight was dismounted in a fixed position with all the supporting weapons of the Cavalry brigade.
Ohh if anyone was interested, this is a good painting that shows the Polish Ulan uniform of the late 1700's. It is pretty much the same uniform used threwout the 1700's but most of the Ulans are wearing the Rogatiewka(Square Hat) thats how you can tell which are the Ulans.
http://www.pinakoteka.zascianek.pl/kossak_w/images/Przysiega_Kosciuszki.jpg