Mandel began working life as a journalist for L'Aurore, a literary and socialist newspaper founded in 1897 by Émile Zola and Georges Clemenceau.
In the 1930s, he played a similar role to that of Winston Churchill in the United Kingdom, highlighting the dangers posed by the rise of Adolf Hitler in Germany.
By contrast, Mandel despite being a conservative and a protégé of Georges Clemenceau, was a close friend of the Soviet ambassador in Paris, Jakob Suritz.
During the September days [of 1938], when he foresaw impending war and played for the first time the role of a second Clemenceau, he had already soaped the hangman's rope for Bonnet.
He was an Anglophile and had inherited Clemenceau's vicious tongue – he had particular contempt for Albert Lebrun, the President of the Republic, and for Deputy Prime Minister Camille Chautemps – but in the view of historian Julian Jackson he was a natural deputy, not a leader, and did not carry the political weight to oppose those - including France's two leading soldiers, Philippe Pétain and Maxime Weygand - who favoured an armistice.
Recounting his 2 o'clock luncheon with the man during Churchill's last trip to France for four years "almost to the day" on 13 June 1940 his account was very favorable, and is as follows: We then returned to the Prefecture, where Mandel, Minister of the Interior, awaited us.
Mandel sought to persuade Lebrun, Herriot, Jeanneney, and as many members of the Cabinet as possible to travel to French North Africa, to continue the fight against the Germans.
Only 25 other deputies and one senator embarked with Mandel on the Massilia on 21 June, including Pierre Mendès France and the former Popular Front education minister, Jean Zay.
Only 57 deputies and 23 senators, dubbed "the eighty", refused to suspend the constitutional laws of France and to give full powers to the government of Marechal Petain, against 569 parliamentarians that supported those proposals.
[13] Mandel was arrested on 8 August 1940 in French Morocco by General Charles Noguès on the orders of Pierre Laval, Prime Minister of the Vichy government.
He was conveyed to the Château de Chazeron via Fort du Portalet,[14] where Paul Reynaud, Édouard Daladier and General Maurice Gamelin were also being held prisoner.
In November 1942, after the German Army moved into unoccupied France and took it over to counter the threat from the Allies, who had just landed in North Africa, the French government at Vichy transferred Mandel and Reynaud to the Gestapo upon their request.
[15] In 1944 the German Ambassador in Paris, Otto Abetz suggested to Laval that Mandel, Blum, and Reynaud should be executed by the Vichy government in retaliation for the assassination of Philippe Henriot, Minister of Propaganda, by the Algiers Committee, the Communist Maquis of the Resistance.
"[17] He added that the members of the Vichy Cabinet were unanimous "in favour of refusing to hand over any hostages in future or to condone reprisals of this nature.
Thomas Couture’s Portrait of a Seated Woman, (c.1850-1855) which was discovered in the Gurlitt trove was identified as having belonged to Georges Mandel from a small hole in the canvas.