The Hussites were a protestant movement following the teachings of Czech reformer Jan Hus who was burned for this teaching by the spoiled Roman catholic church in Konstanz. After his death there was a large rebellion within the Czech lands (also in the southern parts of Poland) that resulted in Hussite wars ... it is one of the most famous part of Czech history when the Czechs fought against the whole Catholic Europe, even Joan of Arc threatened to invade the Czech lands, and also thanks to the phenomenal tactics of the commander Jan Zizka, they won many battles.
The Hussite Wars (also called the Bohemian Wars) were military actions in Bohemia in the period 1420 to circa 1434. The Hussite Wars were first European wars, in which gunpowder weapons (muskets) were massively used. And for example, the English name for "pistol" is derived from the Hussite weapon: "pistala".
The Hussite warriors were basically infantry and they defeated larger armies with heavily armoured knights.
Today Hussitan protestants have one of the largest churches within the Czech lands.