Thompson was born at Allison Gap near Saltville, in Washington County, Virginia, the eldest son of the former Minnie Moore (1878-1966) and her saltmaking laborer husband John Harvey Thompson (1875-1954)[1][2] Probably a distant relative, John H. Thompson had represented Smyth County in the Virginia House of Delegates for one term during the final years of the Civil War (1863–5), and represented both Smyth and adjoining Washington County in the Virginia Constitutional Convention of 1868.
[3][4] However, this boy's still-living grandfather at the time was North Carolina born Calvin Thompson (1846-1926; hence this man's middle name).
Washington County voters elected him commonwealth attorney (prosecutor) at the end of the Great Depression, and he served from 1939 to 1947.
[5] Along with his colleague Theodore Roosevelt Dalton and Senior Judge John Paul Jr., Thompson presided over school integration cases in Western Virginia, implementing the Supreme Court's decision in Brown v. Board of Education.
[6] He married Mary Davis Geurrant (1906-2000) of Florida, who bore two sons and two daughters and outlived him by decades.