Serment du Jeu de paume
Born in Saint-Sever in the Landes department of France, Lamarque was a member of a powerful and influential family. His father Joseph Peter Lamarque (1733–1802) was a lawyer and Seneschal of Saint-Sever. His uncle Jean-Jacques Lamarque (1737–1809) was director of a theological college and was persecuted during the Reign of Terror. Lamarque's father was elected a member of the Third Estate to the Estates General of 1789 and took the Tennis Court Oath. He became a member of the Constituent National Assembly.