In 1939, he was admitted to the Officers Academy of Saint-Cyr within the “Franco-British Friendship” batch. When the Second World War broke out, he, at his request, was sent to North Africa, where he joined the 41st Moroccan Colonial Infantry regiment. Thereafter, he moved to Tunisia within the 43rd Colonial Infantry Regiment, and later on to Niger. Upon returning to Algeria, he joined, near Algiers, “Club des Pins”, a Franco-British camp where special agents were trained to operate behind enemy lines.
In June 1944, after having clandestinely landed at Algeciras, he crossed Spain and returned to France, which was under occupation, but was caught by the Spanish civilian guard and detained till November 1944.
Thereafter the Indochina war broke out. In October 1945, he headed a Laotian commando with which he re-conquered the RC9 villages one after the other, chasing away the Viet Minh troops therein. In March 1946, he returned to France and was sent to the 11th Intervention unit.
In January 1948, Captain Mourier returned to Indochina, within the 2nd BCCP and later on within the 3rd BCCP where he assumed the duties of commando group leader. Little did he know that he was in for a real trouble! On October 7, 1950, at That Khe on the RC 4, during the tragic withdrawal of garrisons from North Tonkin, his battalion was annihilated, except for fourteen of them, including him, who managed to survive.
Repatriated to France in 1950, he left again for Indochina in 1952. He became the commander of a company of the 10th battalion of parachute chasseurs at the orders of Major Chaudrut. Captain Mourier joined the GCMA operating in the rears of Viet Minh and, for close to two years, coordinated the Thai maquis, Miao and Chinese nationalists.
In November 1954, when he returned to France, Major Mourier became the second in command of the 8th RPC, and left with his unit for the Algerian war from 1956 to 1958.
That ended his adventurous military career. He was sent to the Inspectorate of Airborne Troops, and later stayed in Mauritania, and from 1965 to 1967 he served as the E.T.A.P. deputy commander. In 1967, he took over the command of the 8th R.P.I.Ma at Castres. He subsequently stayed in Cambodia from 1969 to 1970, and assumed the position of Cahors departmental delegate from 1969 to 1973 and the position of deputy to the general commanding the 9th Marine Infantry Division.
In 1975, Brigade General Mourier became the deputy of the general commanding the 3rd Military Region of Rennes, before going on retirement in 1975. He left active service on November 1, 1975.
On November 19, 2009, this great volunteer serviceman breathed his last. His funeral took place on November 24, 2009, at the Rochegude church, in the Drôme, followed by burial at the community cemetery. His eulogy was read by General Piquemal, the UNP national president.
Grand officer of the Legion of Honour, General Mourier, during his career, received eleven commendations including five in the Army order. He was equally a holder of the Second World War cross, Overseas Operations cross, Vietnam war cross, military valour cross, volunteer servicemen cross and several other French and overseas decorations.