Born at Toulouse in 1657; died at Castelsarrasin, 16 October, 1730. He was the son of a parliamentary councillor, and entered the army at the age of sixteen. Sent to Acadia in 1683 he served in the Port Royal garrison, studied the conditions of the English colonies, and in 1689 proposed the conquest of New York and Boston. He took part in the unsuccessful Caffinière expedition during which the English destroyed an establishment that he had just begun on Mt. Desert Island, given him in 1688 by Governor de Denonville, together with an estate at the mouth of the Union River on the coast of Maine. Despite his adventerous marriage at Quebec (1687) with Thérèse Guyon, the daughter of a wealthy merchant, he returned to France in financial straits. The king took him under his protection, and in 1691 sent him out to Frontenac, Governor of New France. The latter, meditating an attack on the coast of New England, used all the information he could obtain from the crafty and resourceful young officer, who prepared several memoirs for this special purpose. Under these influential patrons Cadillac advanced, and was successively made captain of an infantry, naval ensign, and, in 1694, commandant of Michillimakinac. In this last office he distinguished himself by his skill in controlling the savages of the West who threatened to unite with the Iriquois; but he likewise took advantage of his position to carry on illegal traffic, and quarraled with the Jesuits who endeavoured to prevent his abuses in the brandy traffic. Returning to Quebec in 1697 he wrote an interesting account of Michillimakinac, and was sent to France by Frontenac for the purpose of making known the latter's views. Falling seriously ill, he promised to erect a chapel in the Franciscan church at Quebec, which promise he fulfilled in 1699. He then proposed to the Court to build a fortified post at the head of Lake Erie, thus to secure the line of fortifications from the West and prevent the Indians of the interior from trading with the English.

In June, 1701, Cadillac founded the city of Detroit, which he called Pont Chartrain in honour of his protector. Here he erected a church and a fort, attracted colonists, parceled out land, gathered the Indians, proposing to civilize them by having them intermarry with the French, and, in 1705, obtained a monopoly of the trade of this post, at first given to a special company. He next aimed at making Detroit "the Paris of New France", suggested the cutting of a canal between Lakes Erie and Huron, and asked that the settlement be made a marquisat in his favour. Having become absolute master of Detroit, with the promise of being appointed its first governor, his ambition eventually led to his undoing. The merchants of Montreal complained that he was depriving their city of trade, Governor Vaudreuil objected to the power that he was arrogating to himself, and the Jesuits protested against abuses in his transactions with the Indians. Recalled to France in 1710, Cadillac subsequentially made Governor of Louisiana, where he arrived in 1712. Entering into partnership with Crozat, he devoted himself chiefly to mining and to trading with the Spaniards. However, in 1716 he was deposed, tried, and sentenced to the Bastille, whence he emerged in 1718, and was restored to favour. In 1722 he obtained a decree whereby he regained possession of his Detroit property and he was later made Governor of Castelsarrasin, department of Tarn and Garonne, where he died. His body was interred in the old Carmels church, since transformed into a prison. Cadillac was shrewd and far-seeing, and would have been capable of great things had not his career been blighted by a caustic temperament and an insatiable desire for gain.

Archives coloniales de France, series C., II; Acadie, II, carton 10; Canada, series C., II, XI-XXXI, series B., XIX-LXIII; Archives des affaires étrangères, Canada, IV; MARGE, Découv. et Etablis., V, 133-346; ROCHEMONTEIX, Jésuits et Nouv. France au 18e siècle, I, 59-74, 242; SULTE, Hist. Can. Franc., VI, viii; RAMEAU, Notes historiques sur la colonie canadienne du Détroit (1861); VERREAU, Quelques notes sur Antoine Lamothe de Cadillac in Revue Canadienne (1883); BURTON, A Sketch of the Life of Antoine de la Mothe Cadillac (Detroit, 1895); IDEM, In the Footsteps of Cadillac (1899).

J. EDMOND ROY