Brother Gregory, influenced by the spiritual heritage of John Huss, founds the Bohemian Unity of the Brethren, which, having functioned within the Utraquist group of Hussites for a decade, separates in 1457 and establishes an independent ministry.

The reform movement bases itself solely on the Bible, and its leaders are able to procure non-Roman ordination from a bishop of the Waldenses.

The roots of this radical and pacifistic stream within the early reformation movement begin in a small village called Kunvald near Žamberk, on the Litice lordship of George Podebrady, in the northeast part of Bohemia.

Theologians and thinkers who provide inspiration for the future Unity of the Brethren are Hussite bishop Jan Rokycana and Petr Chelčický.