In 1622 he formally abjured the Protestant faith, his conversion being partly due to the influence of Marie Vignon. He was already a duke and peer of France; he now became constable of France, and received the Order of the Holy Spirit. He had long since lost the confidence of the Huguenots, but he nevertheless helped the Vaudois against the duke of Savoy. He led the Royal troops against the Huguenots in the Siege of Montpellier in 1622 and was key in finding a negotiated peace.