sentences:  He was made a brevetted lieutenant colonel September 13, 1847 for service in the Battle of Chapultepec, Mexico and honorably mustered out August 25, 1848.Caldwell was elected to the Thirty-first Congress (March 4, 1849 – March 3, 1851) where he again served the chairman, Committee on Expenditures in the Department of the Treasury (Thirty-first Congress).He was not a candidate for reelection to the Thirty-second Congress.