Originally a stone mason in his father's business, he had long service in the New York State Militia, first enlisting in 1845. By 1860 he was Major of the 7th New York Militia and published the Manual of Arms for Light Infantry that year. He and his unit, then in Federal service, were in the defenses of Washington, DC in May and June 1861.
Then, at age 34, he enrolled in New York City and mustered as Lieutenant Colonel of the 65th New York Infantry on 11 June 1861. He was promoted to Colonel on 17 July 1862 after Colonel Cochran was appointed Brigadier General.
 
On the Campaign
He commanded the regiment in Maryland. They were in Pleasant Valley on 16 September, marched nearly to Harpers Ferry and back to Keedysville on the 17th, and arrived on the battlefield of Antietam about 11 a.m. on 18 September 1862.
 
The rest of the War
He was appointed Brigadier General of Volunteers on 23 January 1863. He was later awarded the Medal of Honor for his actions at Marye's Heights, Fredericksburg, VA on 3 May 1863. He led the Brigade on the Gettysburg Campaign and commanded the prisoner of war camp at Johnson's Island, OH over the winter of 1863-64. He returned to the field but was captured in action at the Wilderness, VA on 6 May 1864 and was a prisoner at Richmond, VA and Macon, GA before being exchanged by November 1864. He served briefly in the Western Theater and mustered out in August 1865. He was honored by brevet to Major General of Volunteers in January 1866.