William Stewart Burns was born in Geneva, New York on November 24, 1833. He graduated from Hobart College and was working for the Kansas Relief Committee by 1860.

Soon after the outbreak of the Civil War, Burns journeyed to Missouri to accept a commission as second lieutenant in the Fremont Hussars, organized by Burns’ acquaintance, Alexander S. Asboth, under John C. Fremont. The unit became the 4th Missouri Cavalry in February, 1862. Burns was promoted to captain and remained with the regiment through its campaigns in Missouri and northern Arkansas until February, 1863, when poor health forced a hospital stay in Ironton, Missouri. Following his release, Burns accepted an appointment to the staff of James Dwight, deputy provost marshal for the District of Missouri. Shortly afterward, Burns was appointed judge advocate for the District of Columbus, Kentucky; then appointed acting assistant inspector general for the XVI Corps in July. He participated in the Meridian Campaign, the Red River Expedition, and in operations in northern Mississippi before mustering out with his regiment on September 20, 1864.

Burns had married Sophie Lake Savage Burns (born 1839) on November 24, 1863, and the couple would have four children: (William S., Charles C., Sophie F., and Edward B.). The family lived in Steuben County, New York, where Burns worked as a bookkeeper and clerk for real estate dealers John and Ira Davenport until 1905. William S. Burns died on January 16, 1911, and is buried in Nondaga Cemetery, Bath (Steuben County), New York.