Born: October 2, 1833, Apollo, Pennsylvania.
Died: December 2, 1919, Philadelphia, Pennsylvania.
Buried: Laurel Hill Cemetery, Philadelphia, Pennsylvania.
Benjamin was the son of Smith Agnew and Maria Sterrett, and husband of Anna Cochran.
He graduated from Washington College (now Washington and Jefferson College), Washington, Pennsylvania, in 1854. He then attended the Western Theological Seminary in Pittsburgh, graduating with a Doctorate of Divinity in 1857.
In 1858 he became pastor of the First Presbyterian Church in Johnstown, Pennsylvania (where the famous flood occurred three decades later).
During the American civil war, he was a chaplain in the 6th Pennsylvania Volunteer Infantry, a unit known as the Keystone Zouaves.
He left army service in 1862 and returned to Johnstown.
In 1867, he resigned his pastorate and moved to Philadelphia to serve as pastor of the Westminster Church at 58th and Chester Avenue (1868–70), and the North Presbyterian Church at 6th and Green Street (1870–82). In 1882, he became pastor of the East Liberty Church in Pittsburgh, but returned to Philadelphia in 1884 to pastor the Bethlehem Church at Broad and Diamond Streets in Philadelphia, serving until 1896.
He was heavily involved with the Presbyterian Church at large, serving on a number of boards and as a trustee to two different Presbyterian colleges before retiring in 1912.