Born: February 26, 1821, Concord, New Hampshire.
Died: July 14, 1869, Providence County, Rhode Island.
Buried: Swan Point Cemetery, Providence, Rhode Island.
Leonard was the son of Richard Swain and Sarah Damon, and husband of Julia Maria Allen.
He was educated at Dartmouth College, Hanover, New Hampshire, and Andover Theological Seminary, Newton, Massachusetts.
In 1847 he became a Congregational minister in Nashua, New Hampshire. In 1852, he became pastor of the Central Church, Providence, Rhode Island.