The Polish Hussars (/hzr/, /hsr/, or /hzr/; Polish: Husaria) or Towarzysz husarski, were the main type of cavalry of the first Polish Army, later also introduced into the Army of the Grand Duchy of Lithuania, between the 16th and 18th centuries. When this cavalry type was first introduced by the Serbian mercenary horsemen around the year 1500, they served as light cavalry banners; by the second half of the 16th century hussars had been transformed into heavy cavalry. Until the reforms of 1770s the husaria banners or companies were considered the elite of the Polish-Lithuanian Commonwealth cavalry.