Montgomery was born on a farm near Seymour, Indiana. Montgomery's father, Theophilus Wylie Montgomery, was of Scottish descent and his mother, Susan Harriet Montgomery, was from New York.[1][2]
Montgomery grew up on the family farm and was educated at local public schools before leaving to attend Hanover College, where he was part of the Sigma Chi Fraternity. Graduating in 1881 from Hanover's classical studies department, Montgomery became a school teacher in Reddington while he began studying law. In 1884, he was admitted to the Indiana bar. He moved to Greenfield shortly before returning to his boyhood home of Seymour.[1][2][3][4]
In 1886, Montgomery married Ida E. Harding and had four children. One of them, Theophilus Harlan Montgomery, was a Princeton University graduate and practiced law with his father in Seymour.[2][7]
Montgomery died in Seymour in 1936, at the age of 77.[1]