Leon Roches was a student at the Lycée de Tournon in Grenoble, and followed an education in Law. After only 6 months at university, he quit to assist friends of his father as a trader in Marseilles.
When Leon's father acquired a plantation in Algeria, Leon left France to join him on June 30, 1832. Léon spent the next 32 years on the African continent. He learned the Arab language very rapidly and after only two years was recruited as translator for the French Army in Africa. He served as an Officer (Sous-Lieutenant) of cavalry in the Garde Nationale d'Algerie from 1835 to 1839. General Bugeaud asked him to negotiate with Abd-el-Kader in order to bring about the cessation of hostilities against the French. He is noted as having been highly respected by Arab chieftains.
Under Bugeaud's recommendation, Roches joined the French Foreign Ministry as an interpreter in 1845. In 1846 he became Secretary of the legation in Tanger, and then took responsibilities at the French mission in Morocco.
From 1855 to 1863, Roches served as the French consul general in Tunis, Tunisia. Using his experiences in North Africa, he wrote a book titled Trente-deux ans à travers l′Islam (Thirty-two years through Islam).
By an exceptional nomination, Roches became first-class Consul in Trieste, allowing him to acquire a strong experience in trading matters. After three years, he was appointed Consul in Tripoli. In 1855, he became Consul in Tunis. He often wore Arab dress and was renowned for his abilities with guns and horses.
On October 7, 1863, Roches was nominated Consul General of France in Edo, Japan (now Tokyo, Japan). His great rival was the British consul Harry Parkes. The French government took the side of the Tokugawa Bakufu and thus was not very popular in Japan after the Meiji Restoration.
Roches advocated the use of strength against the anti-foreign adversaries of the Shogunate. He fully supported the 1864 allied Bombardment of Shimonoseki.
Later he founded a French school (1865) and among his pupils were many hatamoto (direct retainers of the Shogun).
He formed a trading concern with Kozuke Oguri to expand commerce between the two nations and to monopolize the exports of raw silk. For the latter purpose he founded the Societe Generale in Paris, but due to lack of funds the enterprise failed.
He was all along in favor of the Shogunate and was instrumental in sending Akitake Tokugawa, the younger brother of Shogun Yoshinobu, to attend the World Exhibition in Parls and to study in Europe (1867). Evert after the Shogunate fell he continued supporting them. Returned home in disappointment when he learned that the Shogunate had no chance of coming into power again (1868).