Among his ancestors were Protestant pastors from the Rhenish Palatinate or Baden-Wuerttemberg who had sought refuge in France in the seventeenth century, one of them being Andreas Cellarius.

Charles Mast left the prison as Chief of Staff of the 19th Army Corps (France) in North Africa in 1942.

Clark met secretly with various military and civilian representatives of the resistance, including Colonel Jousse, Charles Mast, and Bernard Karsenty, Deputy José Aboulker.

General Mark Wayne Clark, considered Charles Mast as spokesman for Henri Giraud and the head of the French armies in North Africa.

Mast, Chief of Staff of the Army Corps of Algiers, mediated between Giraud and Charles de Gaulle especially for military questions.

Charles Mast took command of the division march in Casablanca in 1942 and was appointed chief of military missions in Syria and Egypt in 1943.

General Georges Revers [fr], intended to have him appointed as High Commissioner of French Indochina instead of Léon Pignon.

Until his death, Mast had little confidence in France's western allies chances of success against a collaborated Communist attack.