He was the son of Charles of Montmorency and Pernelle de Villiers.
In 1382, at the age of 12, he accompanied the King on a campaign in Flanders, and took part in the battle of Rosebeek.
[2] In 1391, the parliament of Paris confirmed the ancient privilege of the Montmorency family to be the first to buy fish delivered to Paris through their town of Saint-Bris at the usual price.
[2][3] Despite his youth, King Charles VI appointed Jacques of Montmorency as chamberlain and Duke Philip II of Burgundy granted him the same position at his court.
[2][3] He was married (1399) to Philippine de Melun, dame de Croisilles (d.1420)[1] Illegitimate children: