THOMAS MONTGOMERY, the sixth child of William and Mary, was born in Washington County, Pennsylvania on May 21, 1791, and he moved with his parents to Clark County, Indiana in 1806. He is mentioned in his father's 1818 will in which he was "released" from repaying his father "money which I (William) have heretofore paid as special bail in certain suits in Clark Circuit Court" on behalf of Thomas and his brother, William Montgomery. (Thomas was also bequeathed "20 bushels of corn" in that will, which at least suggests that Thomas was probably living close enough to his father's farm at the time to collect the bequest.)

Warren Montgomery, a family genealogist from Frankfort, Illinois, has looked for several years for, more reliable data on Thomas. He has found a Thomas Montgomery, born in Pennsylvania in 1791 (this fits exactly), who was living in Hammond Township, Spencer County, Indiana, at the time of the 1850 census. Spencer County is about 80 miles southwest of Clark County, on the Ohio River. This Thomas had a wife, Sarah, who was born in Kentucky in 1793, and a son, Robert Montgomery, who was born in Louisiana in 1832. Thomas was also there in the 1840 census.

Fred Walker, a family genealogist from DeKalb, Illinois has a copy of a court document dated shortly after the death of William, in which one of Thomas' brothers testified that Thomas had removed to the lower country. This was a term used to refer to the southern states. As we have seen a Thomas Montgomery of the correct age and born in PA appears in the 1850 census of Spencer County with a wife named Sarah and a son named Robert born in LA.

Thomas' birth date and location are documented in Baird's history of Clark County, Indiana.