This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Jan Hus, a Prague theologian and preacher influenced by John Wycliffe, was burned as a heretic at the Council of Constance in 1415 despite having traveled there under a promise of safe conduct, and his execution radicalized his followers across Bohemia. Their central demand, that communion be offered in both bread and wine to all believers rather than bread alone to the laity, a practice called Utraquism, challenged a central practice of the medieval Catholic Church, and the wider Four Articles of Prague added calls for free preaching, apostolic poverty for clergy and the punishment of public sin by proper authority.
Five successive popes authorized crusades against the Hussites as a heretical movement between 1419 and 1434, and all five failed to subdue Bohemia, in significant part because of the war wagon tactics the Hussite general Jan Zizka developed, mobile fortified wagons that let comparatively small Hussite forces repel much larger crusading armies in the field. No crusade fought in the era, whether in the eastern Mediterranean, the Baltic or Bohemia, carried greater religious and juridical weight in the eyes of the popes who called it, and none of the five achieved its object.