William S. Henay was born around 1832 in Ireland to William Henay and Mary Clinton. He eventually immigrated to America and settled in Massachusetts. He earned a living as a painter. He married Catherine Flaven in Boston, Massachusetts, on February 7, 1854, and they had at least seven children: William, born around 1855; Fannie, born around 1857; Catherine, born around 1860; Emma, born around 1864; Benjamin, born around 1868; Laura, born around 1871; and Stephen, born around 1875. By the early 1860s, they were living in Roxbury, Massachusetts.
Henay enlisted in the Union army on May 22, 1861, and he mustered in as a corporal in Company D of the 1st Massachusetts Infantry. According to his service records, he was 5 feet, 8 inches tall, with dark hair and blue eyes. He reportedly deserted from the regiment around June 9, 1861. He returned later that summer, and army officials demoted him to private on August 7. The regiment took part in the Peninsula campaign and the Second Battle of Bull Run.
He was reported missing on June 30, 1862, after the Second Battle of Bull Run, but he eventually returned to the regiment. He fell ill that fall, and officials sent him home to Roxbury to recover. In December 1862, an official noted that they had “not heard from [him] since” he returned home, and they initially listed him as a deserter. The charge was later removed, and he was discharged for disability on November 20, 1862. As a surgeon explained, Henay suffered from “chronic disease of the knee joint which absolutely unfits him for military duty.”
He returned to the Union army on March 10, 1864, mustering in as a private in Company F of the 56th Massachusetts Infantry. The regiment took part in the Overland Campaign, the siege of Petersburg, and the Appomattox campaign. He mustered out on June 28, 1865.
Henay returned to Roxbury after the war and resumed his work as a fresco painter. The family moved to Concord, New Hampshire, in the late 1860s, and by 1870, he owned $300 of personal property. He applied for a federal pension in November 1878 and eventually secured one. They probably moved to Boston in the 1880s, and he died there of “strangulation by meat in throat” on January 11, 1891.