He was educated at Dickinson Seminary, later Lycoming College and became a civil engineer
He led a regiment and then a brigade in the American Civil War. In 1861, Curtin served as a private in the 2nd Pennsylvania Infantry. On September 9, 1861, he was commissioned a captain in the 45th Pennsylvania Infantry.
Curtin was promoted to the rank of major on July 30, 1862, and lieutenant colonel on September 4 of the same year.
He became the regiment"s colonel on April 13, 1863. In the Army of the Potomac, Curtin served in IX Corps.
He led the regiment at the Battle of South Mountain and the Battle of Antietam in the place of Colonel Thomas Welsh, who was holding brigade command.
Welsh return to command of the regiment for the Battle of Fredericksburg.
When Welsh was promoted to the rank of brigadier general, Curtin became the regiment"s commander. After IX Corps was transferred west, Curtin led the 45th Pennsylvania in the Siege of Vicksburg. He was absent, however, from the Knoxville Campaign.
When IX Corps returned to the Army of the Potomac in 1864, Curtin led his regiment at the Battle of the Wilderness in the 2nd Division of Brigade
General Robert B. Potter. Curtin took command of 1st Brigade, 2nd Division, on May 11, 1864, after Colonel
Zenas Bliss was injured at the Battle of Spotsylvania Court House. He led the brigade at the Battle of Cold Harbor and continued in command until June 18, when he was wounded in the Second Battle of St. Petersburg.
(Colonel Simon Goodell Griffin led the other brigade of the division)
Curtin led his brigade again in the Siege of St. Petersburg from August 21 to January 13, 1865, before going on leave.
(Colonel Sumner Carruth led the brigade during Curtin"s absence) After this absence, Curtin resumed brigade command on February 11, serving until April 24. After the Confederate surrender, in the Department of Washington, Curtin led the 3rd Division, IX Corps, in place of Brigade General John Hartranft from May 4 to July 8 and then his old brigade from July 8 to July 17, 1865.
Curtin became a brevet brigadier general on October 12, 1864.
He was mustered out of the volunteer service on July 17, 1865. Colonel Curtin died in Bellefonte, Pennsylvania.
He was buried at the Union Cemetery in Bellefonte.