Montgomery County was formed from Fincastle County in 1776, and the county court first met on 7 January 1777. Part of Botetourt County was added in 1790. Part of Pulaski County was added in 1842. The county was named for Richard Montgomery, who was killed in the American assault on Quebec late in 1775.

Fincastle County was created from Botetourt County in 1772, and the county court first met on 5 January 1773. Fincastle County became extinct on 31 December 1776 when it was divided to form Montgomery, Washington and Kentucky Counties. The county was named probably for George, Viscount Fincastle, Lord Dunmore's son; for John Murray, fourth earl of Dunmore, Viscount Fincastle; or for the town of Fincastle, Virginia, which was established in 1772 and named for George, Viscount Fincastle.

A fiduciary is a confidential and legal relationship which binds one person to act on behalf of another. A fiduciary is also a person who acts as a trustee for another.

An Administrator is a person appointed by the court to manage the assets and liabilities of a person who dies without having written a valid will. An administrator may also be appointed if the testator leaves an incomplete will naming no executor, or if the named executor cannot or will not serve.

Administrators' Bonds are bonds that administrators were required to take out with the justices of the court to guarantee proper execution of their positions. The obligation was made binding by a money guarantee. The bonds show the names of the administrator and their sureties, the date, amount and condition of the obligation, name of the deceased, and signatures.