Major, 18th Pennsylvania Cavalry. Promoted from Captain, Company D, to regimental Major to fill an original vacancy on January 7, 1863. He enlisted during the Civil War, and was Assistant Adjutant General under Gen. Russell after returning from South Carolina, where he was stationed and fought all through the storming of James Island, on Gen. James' staff; came home sick and remained some months, doing duty at Harrisburg under Gen. Russell. He was commissioned Major of the 18th Pennsylvania Cavalry. Discharged on January 14, 1864, but recommissioned and rejoined regiment. He was wounded in the right leg and captured at Mine Run, Virginia, on May 5, 1864. Right leg amputated at the hip by circular technique by Dr. Taylor, Wade Hampton's chief surgeon. After being a prisoner seven weeks, was captured by General Sheridan and sent to West Chester. Discharged on October 3, 1864. Date of discharge also listed as October 30, 1864.

William Baldwin, so named for another botanical friend of his father. He resided successively at Athens, Towanda, Altoona, Spruce Creek, Spangleville, Tipton, Waverly, and West Chester. He was commissioned postmaster at West Chester June 3, 1865, and held the position nearly twelve years, but the pain in his stump wore upon his health and made him unfit for any work or duty, so that he resigned before the expiration of his term. Married Celestia H. Overton on June 8, 1853 in Athens, Bradford, Pennsylvania. Filed for a pension on November 22, 1864, application number 55,466, certificate 35,767. Wife Celestia filed for a widow's pension on July 27, 1878, application number 238,547, certificate number 186,314.

See 18th PA Cav for a virtual cemetery of the 18th Pennsylvania Cavalry.