After he war, he became a lauded gallery art owner and a recognized historian of WWII in France.
Résistant, he used as one of his pseudonym his stepfather's last name, He was Jean Moulin's main secretary of the clandestine direction of Operations in Occupied France. He is the penultimate Compagnon de la Libération to die.
Upon Cordier's death, Hubert Germain became the last surviving resistance fighter of the 1,038 (including six women) honored by Gen. Charles de Gaulle with the title Companion of the Liberation.
In 2018, President Macron awarded him the Grand Cross of the Legion of Honor, the highest level of that national order.