Pierre Joseph Auguste Messmer was born in Vincennes in 1916. He graduated in 1936 in the language school ENLOV and the following year at the "Ecole nationale de la France d'outre-mer" (National School of Oversea France). He then became a senior civil servant in the colonial administration and became a Doctor of Laws in 1939. In the outbreak of World War II, he was sous-lieutenant of the 12th regiment of Senegalese tirailleurs, and refused France's capitulation after the defeat. He then hijacked in Marseille an Italian cargo ship (the "Capo Olmo"), along with his friend (a future French General), and sailed first to Gibraltar, then London and engaged himself in the Free French Forces as a member of the 13th Demi-Brigade of the French Foreign Legion. Messmer then participated to the campaign in Eritrea, in Syria, in Libya, participating to the Battle of Bir Hakeim, and in the Tunisia campaign. He also fought at the Battle of El Alamein in Egypt. He joined in London General Koenig's military staff and participated in the landings in Normandy in August 1944 and the Liberation of Paris.