At the time of the Armistice, he was a liaison officer on board HMS "Warspite" and played an important role in the delicate negotiations between Admiral Andrew Cunningham and Admiral René-Émile Godfroy for the fate of the Force X, becoming the main architect of compromise signed between the two admirals, which decided on the status of the French squadron in Alexandria. He then traveled to London to join the forces of Free France, arriving on 20 July 1940.