Frederick was a member of the family of Wettin, which since his day has played a prominent part in the history of Europe, and he owed his new dignity to the money and other assistance which he had given to the emperor during the Hussite war.
The anti-Roman or Hussite movement was largely a democratic one, and it is therefore natural that the national language rather than Latin should have been used in the writings that belong to this period.
It suffered greatly during the Hussite war, and still more during the Thirty Years' War, in the course of which it was besieged and captured by the elector of Brandenburg, John George (1620), fell into the hands of Wallenstein (1633), and, in the following year was burned by its commander before being surrendered to the elector of Saxony.
Wycliffe's ideas, conveyed to the continent, precipitated the outbreak of the Hussite storm in Bohemia.
These privileges still remained to them at the outset of the religious Reformation, which the Silesians, in spite of their Catholic zeal during the Hussite wars, accepted readily and carried out with singularly little opposition from within or without.
In return Hussite mercenaries fought on the Polish side at Tannenburg, and Czech patriots repeatedly offered the crown of Bohemia to Wladislaus.
After an unsuccessful attempt to storm Zatec the crusaders retreated somewhat ingloriously, on hearing that the Hussite troops were approaching.
The nobles, who though favourable to the Hussite cause yet supported the regent, promised to act as mediators with Sigismund; while the citizens of Prague consented to restore to the royal forces the castle of Vysehrad, which had fallen into their hands.
Indeed, from first to last, the Polish gentry as a body took good care to pay and fight as little as possible, and Casimir depended for the most part upon the liberality of the Church and the Prussian towns, and the valour of the Hussite infantry, 17c,000 of whom, fighting on both sides, are said to have perished.
Unable to maintain himself there he marched to southern Bohemia, and after defeating the Romanists at Sudomef - the first pitched battle of the Hussite wars - he arrived at Usti, one of the earliest meeting-places of the Hussites.