Harold enlisted at New York
City, NY on 11 February 1943. He volunteered for parachutist duty
and went to the jump school at Fort Benning, GA.
On 6 August 1943 Pvt
O'Brien was transferred from the Parachute School to Hq 2nd, 508th PIR
which was then at Camp Mackall, NC.
The following day he was
shifted to Company F and then on 2 September 1943 was transferred to an
destination was the 504th PIR as he was wounded on Hill 1205, Venafro,
Italy during the Salerno Campaign whiler serving with that regiment.
returned to the U.S. aboard the USS Ariel (AF-22) which set sail from
Trinidad (British West Indies) on 29 November 1945 and arrived in New
York City on 1 December 1945. He was discharged 4 days later.