Following the Armistice of 22 June 1940, he remained in the Army of Vichy France and from July 1940 to September 1941, he was the adjutant to the general commanding the 13th Military Division at Clermont-Ferrand and military commander of Puy-de-Dôme. During these times, de Lattre implemented government directives relating to improving discipline and cohesion in the army, believing that the regime of Marshal Philippe Pétain was acting in defence of the national interest. Keen to encourage young men, he opened several field schools and military instruction centres – built up by Alsatian soldiers – with the aim of producing capable officers and generals, trained in team work and able to spread their experience across the board of the armistice army. Promoted to général de division (equivalent to Major General in Anglophone countries), he was the commander-in-chief of troops in the protectorate of Tunisia where he opened another military instruction centre. Following this four-month deployment from late September 1941 to 2 February 1942, he was recalled to France after a dispute with his superior Alphonse Juin and was reassigned. Returning to France, de Lattre took charge of the 16th Military Division, based in Montpellier. Following the Allied landings in French North Africa on 8 November 1942, Germany occupied southern France and disbanded the Vichy Army. De Lattre was arrested and imprisoned for several months.