Colbert Caldwell (Coldwell), lawyer, jurist, and politician, son of Nathaniel Caldwell, was born in Bedford County, Tennessee, on May 16, 1822. After engaging in the Santa Fe trade from 1840 to 1845 he returned to Tennessee, studied law, and was admitted to the bar in Shelbyville in 1846. He began his career as an attorney in St. Francis County, Arkansas, and represented that district in the state legislature before moving to Texas. He settled first in Mansfield in 1859. Before the outbreak of the Civil War he had moved to Navasota. By the end of the war county tax rolls described Caldwell as the owner of eleven slaves and an estate valued at more than $17,000.
He was named to the bench of the Seventh Judicial District by provisional governor A. J. Hamilton on August 23, 1865. On October 18, 1867, he was appointed associate justice of the Texas Supreme Court by Gen. Philip H. Sheridan, commander of the Fifth Military District. Campaigning for a seat at the Constitutional Convention of 1868–69, Caldwell, whose outspoken Republican partisanship had earned him a reputation among Democrats as a rabble-rouser, survived an assassination attempt by a White mob during a speech before a mostly Black audience in Marshall on December 31, 1867. Although badly frightened by the incident, he resumed his campaign and won the seat. As a delegate Caldwell helped lead the moderate Republican faction and was nominated for the presidency of the convention. He chaired a select committee of that body, which investigated the rampant postbellum lawlessness and violence in the state. The convention also sent Caldwell and Morgan Hamilton to Washington, D.C., to lobby for their appointment of loyal Republicans to state office and to win authorization for a state militia to quell disorder. However, increasingly perceived by radicals within his party as unsympathetic to freedmen's aspirations and the goals of congressional Reconstruction, Caldwell was removed from his position on the Supreme Court by the commander of the Military District of Texas on October 31, 1869. In 1876 he was appointed United States collector of customs at El Paso. Upon retirement from that post he and his family left the state for Kansas and later settled in California. Caldwell and his wife, the former Martha Julia Mitchie of Lawrence County, Tennessee, had eight children. Caldwell died in Fresno, California, on April 18, 1892.