French soldier, explorer, and ascetic who is best known for his life of study and prayer after 1905 in the Sahara Desert.

Foucauld first visited North Africa in 1881 as an army officer participating in the suppression of an Algerian insurrection. He led an important exploration of Morocco in 1883–84 and, at a later time, studied the oases of southern Algeria. In 1890 he became a Trappist monk but soon left that order to become a solitary ascetic in Palestine. In 1901 he became a missionary priest, establishing himself initially in southern Algeria and then at Tamanrasset in the Ahaggar (Hoggar) Mountains of the Sahara. One of the first Frenchmen to enter the area after its conquest, Foucauld built a rough stone hermitage for himself on the peak of Mount Assekrem and lived there among the native Tuareg, whom he encouraged to be loyal to the French government, and compiled a dictionary of their language. In 1916 Foucauld was killed by local rebels during an uprising against France.