Dadjo served in the British Army during World War II and in the French Army in the Indochina and Algerian conflicts. At the time of Togo's independence in 1960, he was the longest-serving and highest-ranking Togolese in the French Army. He held the rank of Captain and commanded Togo's tiny defence force, the "Garde Togolaise". He was promoted to Major and eventually to Colonel after the 1963 "coup d'état" and served as head of the military cabinet of President Nicolas Grunitzky.