BACKUS, Isaac, clergyman, born in Norwich, Connecticut, 9 January 1724; died 20 November 1806. He became identified with the "Separatist" movement, began to preach in 1746, was ordained in Middleborough, Massachusetts, 13 April 1748, and became pastor at Titicut, in that town, of a new Congregational society, which had been formed in consequence of a dispute regarding the settlement of a minister. In 1749 some of his congregation began to sympathize with the Baptists, and he finally united with these and formed a Baptist Church in Middleborough in 1756, having been immersed in 1751. He held open communion for some years, but at length abandoned it. Throughout his life he was an earnest and consistent advocate of the utmost religious freedom. In 1774 he was sent as the agent of the Warren association of Baptist Churches to claim from congress, for the Baptists, the same rights as those accorded other Churches. He vindicated his course by a paper in the " Boston Chronicle," 2 December 1779, arguing against a proposed article in the Massachusetts bill of rights. In 1788 he was a delegate to the convention that adopted the federal constitution, and made a speech in its favor. Dr. Backus was for thirty-four years a trustee of Rhode Island College, now Brown University. He was a voluminous writer, his most important work being a "History of New England, with Special Reference to the Baptists" (3 vols., 1777-'96), with an abridgment, bringing the work down to 1804. A new edition, carefully edited by Rev. David Weston, of Madison University, was published under the auspices of the Backus historical society of Newton Centre, Massachusetts. (2 vols., 1871). This work, though partisan, is still valuable to the student of New England history. Dr. Backus also wrote a history of Middleborough in the 3d volume of the Massachusetts historical collections. See Sprague's " Annals of the American Pulpit."