He graduated at Trinity College, Dublin, and studied philosophy in the University of Edinburgh under Dugald Stewart.
He died very suddenly at Stonehouse, Stillorgan Road, Dublin on Wednesday, 4 December 1839, having preached on the previous Sunday, and married a couple that very morning.
He married Mary Allman, and left two sons (John Strong Armstrong, A.B., president of the Dublin Historical Society, and Rev.
George Allman Armstrong, A.B., originally a barrister, who succeeded him in 1841 at Strand Street) and four daughters.
A petition from his widow is printed in Parliamentary Debates on the Dissenters' Chapels Bill, 1844.