 The act of the Warsaw Confederation, which took place during the convocation sejm of 1573, provided guarantees, at least for the nobility, of religious freedom and peace.It gave the Protestant denominations, including the Polish Brethren, formal rights for many decades to come.Uniquely in 16th-century Europe, it turned the Commonwealth, in the words of Cardinal Stanislaus Hosius, a Catholic reformer, into a "safe haven for heretics".