[3] During the Civil War Carpenter volunteered as a private then was elected captain of volunteers on March 24, 1862, appointed lieutenant colonel on September 26, 1864, and brevet colonel on July 12, 1865 "for efficient and meritorious services" when he was in charge of commissary of subsistence in Sherman's Army on the march to the sea.

At the expiration of his term he was appointed Second Comptroller of the Treasury of the United States, where he served two years, from January 1876 to September 1877.

[3] In 1878 Carpenter was elected to Congress to represent Iowa's 9th congressional district, which was then made up of the sparsely-settled northwestern quadrant of the state.

[3] In 1883, he again ran for the state legislature, winning election to the Iowa House of Representatives for a two-year term, and serving from 1884 to 1886.

[3] Returning to Iowa from Washington, District of Columbia for the last time, he served as postmaster of Fort Dodge from 1889 to 1893.