Benjamin F. O’Connor was born on January 14, 1843, in New York to Theodore and Eunice O’Connor. His father was a farmer who owned $300 of personal property by 1860. The family lived in Clayton, New York, until the 1850s, when they moved to Metomen, Wisconsin. By 1860, he was working as a farmer.
O’Connor enlisted in the Union army on August 21, 1862, and he mustered in as a private in Company H of the 32nd Wisconsin Infantry later that day. He was eventually promoted to sergeant. The regiment took part in the Vicksburg Campaign, the Atlanta Campaign, the March to the Sea, and the Carolinas Campaign, and O’Connor mustered out on June 12, 1865.
O’Connor returned to Wisconsin after the war and resumed his work as a farmer. He married a woman named Elsie, and their son William was born around 1869. His wife probably died in the 1870s. By 1880, he was living in his mother’s household in Springvale, Wisconsin. He applied for a federal pension in April 1895 and eventually secured one. He died in Wisconsin on May 10, 1899.