O'Connor was born on July 15, 1843, in East Hereford, Canada East. His official residence was listed as Lodi, Wisconsin.[2] He joined the US Army from West Point, Wisconsin, in June 1861, and mustered out in July 1865. He died in Orting, Washington, and was buried in Washington Soldiers Home Cemetery.[3]
Medal of Honor citation
His award citation reads:
For extraordinary heroism on March 31 & 1 April 1865, while serving with Company A, 7th Wisconsin Infantry, in action at Gravelly Run, Virginia. On 31 March 1865, with a comrade, Sergeant O'Connor recaptured a Union officer from a detachment of nine Confederates, capturing three of the detachment and dispersing the remainder, and on 1 April 1865, he seized a stand of Confederate colors, killing a Confederate officer in a hand-to-hand contest over the colors and retaining the colors until surrounded by Confederates and compelled to relinquish them.