In 1562 most of the inhabitants of Meaux had become Protestants. In the First War of Religion Joachim de Montluc, sent by the king, proceeded with rigour against them. They were still sufficiently powerful in 1567 to attempt to carry off, in the vicinity of Meaux, Catherine de' Medici and Charles IX; and so for that reason, shortly after St. Bartholomew's day in August 1572, Charles IX ordered the massacre of the Protestants of Meaux. At the château of Fontainebleau, built by Francis I, was held the theological conference of 4 May 1600, between the Catholics (Cardinal du Perron, de Thou, Pithou) and the Calvinists (du Plessis Mornay, Philippe Canaye, Isaac Casaubon).