Paul W. answered 04/15/19
MA Military & Diplomatic History with 10+ Years of Teaching Experience
Military 'Fashion', both in the specific meaning of the design of uniforms and in the broader meaning of trends in the conduct of warfare, is a funny thing! Regardless of whether something that is successful in particular circumstances is likely to work under very different circumstances, success seems to be irresistible to a nation's armed forces.
According to most accounts, the first 'hussars' were formed in the late-Middle Ages in the Kingdom of Hungary from refugee Serbians fleeing the conquest of their homeland by the Ottoman Empire. It was primarily the success of these original hussars - lightly armed cavalry - against Ottoman cavalry that earned these soldiers fame beyond the frontiers of Hungary (the Polish Army also fielded cavalrymen known as hussars whose exploits also brought this particular type of soldier widespread acclaim, though Polish hussars were more heavily armed than their Hungarian counterparts).
By the 18th century, the 'hussar' had become a category of cavalry - specifically, light cavalry - commonly found in most European armies. They were distinguished from other categories of light cavalry by a combination of their intended function in warfare, their principal weapon with which they were armed, and their distinct style of uniform. The dragoon originated as a form of mounted infantry, though it seems to have lost this role by the 18th century. The lancer, as the name implies, used a lance as his primary weapon.
The hussar, unlike the dragoon, was never intended to serve as a form of mounted infantry. The hussar, unlike the lancer, used a curved saber as his primary weapon. As lightly armed cavalry, hussars were ideally suited to performing reconnaissance - scouting ahead of the main body of a field army - and harassing enemy troops and supply lines.
Granted, the categories of cavalry known as 'dragoons' and 'lancers' could also perform these functions. But the hussar was also distinguished by their fantastic style of uniform, patterned after Eastern European costume: a short fur trimmed jacket liberally decorated with horizontal braids across the chest, a smaller jacket of similar design slung over the shoulder, and the tall, circular fur hat. In an age in which members of the nobility raised their own units for service in their nation's (or, indeed, another nation's) army, the dashing Hussar style uniform served as an excellent draw to attract recruits.