A son of Jean de Saint-Lary, who was a military governor of Metz, he was brought to court by the duke of Épernon.

[2][3] His estate of Seurre in Burgundy was created a duchy in the peerage of France (duché-pairie) in his favour under the name of Bellegarde, in 1619.

[1] Bellegarde was an illustrious noble at the French court who sided with Gaston, Duke of Orléans.

During the turbulent years of 1629 and 1630, in which Marie de Medici and Gaston had reputedly allied against Cardinal Richelieu, there were rumours that Bellegarde kept their agreement in a precious necklace he wore at court.

Upon hearing of this, the king started moving towards Burgundy with an army and took Dijon, after which Bellegarde fled Now in possession of Dijon, the king ordered the Parlement to issue an edict against Gaston's followers.