The McKinleys were of English and Scots-Irish descent and had settled in western Pennsylvania in the 18th century, tracing back to a David McKinley who was born in Dervock, County Antrim, in present-day Northern Ireland. There, the elder McKinley was born in Pine Township, Mercer County.The family moved to Ohio when the senior McKinley was a boy, settling in New Lisbon (now Lisbon). He met Nancy Allison there and married her later. The Allison family was of mostly English descent and among Pennsylvania's earliest settlers. McKinley's regiment again suffered many casualties, but the Army of the Potomac was victorious and the Confederates retreated into Virginia. The regiment was then detached from the Army of the Potomac and returned by train to western Virginia.