Civil War Medical Figure. Receiving his medical credentials from the University of Maryland in 1844, this native of Fairfax County, Virginia migrated north, and ultimately established a respected medical practice in Gettysburg, Pennsylvania. On the first three days of July 1863, the battle of Gettysburg interrupted and traumatized this region, and when the aggression ceased, untold deaths and casualties lay in its wake. In the face of real or imagined allegations that he was a "Southern sympathizer," O'Neil mutually cared and treated scores of Federal and Confederate soldiers in the battle's aftermath. Beginning approximately at this time, he began making simple memorandums on the fringes of the pages of his "Physician's Hand Book of Practice" that documented the identities of slain southern soldiers and their grave sites that dotted the battlefield and its environs. This early compilation was rudimentary, and it was done while the doctor was on errands or on medical "house calls." He later changed to a better system, and transcribed these records to what would be become known as his "Journal of Confederate Burials." In time, Southern families began to make inquiries to him as to the whereabouts of their loved one(s). He was unable to offer assistance in many of these requests; however, the instances where he was in a position to help, he would personally locate, exhume and afterwards enclose the remains in a wood crate in preparation for shipment to the bereaved family. He never profited from these endeavors, and his charge to complete this unattractive task never approached an amount that would be advantageous to his monetary welfare. From all accounts, his intentions were strictly humanitarian. As time passed, the marked graves of many of these Confederate soldiers were eliminated by weather and the intentional or inadvertent acts of individuals. If not for his records, the identities of these soldiers would have become one of anonymity. His daughter donated the records to the Gettysburg National Military Park in 1943, and they continue to be a valuable asset to historians and genealogists today.