Jan Hus did oppose the Roman Catholic practice of withholding the cup from the people.
The old Czek Republic had originally been under the jurisdiction of the Orthodox East (Byzantine Empire). When it was taken over (as a result of war) by the West, Roman Catholicism was forced on the people there. Some Bohemians and Moravians banded together in a reform effort, calling themselves the Unitas Fratrum. Their efforts were eventually crushed and they were wiped out, but their writings remained. Jan Hus and his allies designed to resurrect the mission of the Unitas Fratrum, and succeeded, although Hus was martyred. Persecuted by the Roman Catholic Church, the group took refuge on the estate of Count Nicholas von Zinzendorf, who was sympathetic to their mission. Eventually, the Unitas Fratrum moved to Britain and then to the American colonies, establishing the first Moravian community in the New World: Bethlehem, PA. Their second colony was Salem, North Carolina, now part of Winston-Salem (my home town).
That may be more than you were looking for, or you may have already discussed it in another thread, but if not, I hope this helps.