At the time of the Nazi invasion in 1940, Joliot-Curie managed to smuggle his working documents and materials to England with Hans von Halban, Moshe Feldenkrais and Lew Kowarski. During the French occupation he took an active part in the French Resistance as a member of the National Front. Collins and LaPierre in their book "Is Paris Burning?" note that during the Paris uprising in August 1944 he served in the Prefecture of Police, manufacturing Molotov cocktails for his fellow insurgents, the Resistance's principal weapon against German tanks. The Prefecture was the scene of some of the most intense fighting during the uprising.