After the German invasion of the free zone in November 1942, Debré's political Pétainism disappeared, and in February 1943, he became involved in the French Resistance by joining the network Ceux de la Résistance (CDLR).

During the summer of 1943, General Charles de Gaulle gave Debré the task of making a list of prefects who would replace those of the Vichy regime after the Liberation.

Michel Debré became the Garde des Sceaux and Minister of Justice in the cabinet of General de Gaulle on 1 June 1958.

[7] He played an important role in drafting the Constitution of the Fifth Republic, and on its acceptance he took up the new position of Prime Minister of France, which he held from 8 January 1959[8] to 1962.

After the 1962 Évian Accords referendum that ended the Algerian War and gave self-determination to Algeria was approved by a nearly ten-to-one margin, de Gaulle replaced Debré with Georges Pompidou.

Defeated, in March 1963 he decided to go to Réunion, an island that he had visited for less than 24 hours on 10 July 1959, on a trip with President de Gaulle.

The choice reflects Debré's fear that what remained of the French colonial empires would follow the path trodden by Algeria: that of independence for which he was not sympathetic.

In that role, he became a hated figure of the left because of his determination to expropriate the land of 107 peasant farmers and shepherds on the Larzac plateau to extend an existing military base.

Michel Debré arrived on the island of Réunion in April 1963 and succeeded in being elected Député for Saint-Denis on 6 May despite local opposition to the ordonnance Debré, a law that he had introduced in 1960 to allow civil servants in the overseas departments and territories of France to be recalled to Metropolitan France if they were suspected of disturbing public order.

He personally fought to get Paris to create a second secondary school on the south of the island, in Le Tampon, when at the time there was only one, the Lycée Leconte-de-Lisle, which catered for many thousands of inhabitants.

[citation needed] From 1968 to 1982, Debré forcibly relocated over 2,000 children from Réunion to France, to work as free labour in Creuse.