Lucien Charles Xavier Saint was born on 26 April 1867 in
Évreux, Eure, where his father was a doctor. He obtained a law degree in Paris, and began his career as a lawyer before entering the
prefectorial service in 1896 as a chief of staff. He was chief of staff of the prefecture of Aube, then sub-prefect of Rochefort. In 1902 he married the daughter of
Georges Trouillot, the Minister of Commerce, and became chief of staff to his father-in-law. He was next chief of staff to the Minister
Jean Cruppi. He was appointed prefect of
Nièvre in 1906, then of
Ille-et-Vilaine in 1909.
World War I (1914–1918) began in July 1914. In 1915 he was appointed Prefect of
Toulouse, and in 1918 to
Bouches-du-Rhône. In 1919 he was appointed by
Georges Clemenceau to organize reconstruction of the Aisne department, which had been devastated by the war. ==Tunisia==