 In the following century, this was challenged again by the Protestant Reformers, including Martin Luther, John Calvin and Huldrych Zwingli.The Council of Trent referred to the pope the question whether the petition of the Holy Roman Emperor to have the use of the chalice allowed in his dominions be granted; in 1564 Pius IV did grant this permission to some German bishops, provided certain conditions were fulfilled.However, his concession was withdrawn in the following year.