Thomas J . McKean Thomas Jefferson McKean ( August 21 , 1810 – April 19 , 1870 ) was an American engineer , soldier , politician , and farmer . A West Point graduate , he fought in the U . S . Army during the Seminole Wars , in the Mexican – American War , and he served as a general in the Union Army during the American Civil War . Early life and career . Thomas J . McKean was born in 1810 in the borough of Burlington located in Bradford County , Pennsylvania . He entered the United States Military Academy in West Point in 1827 , and graduated four years later , standing 19th out of 33 cadets . McKean was commissioned a brevet second lieutenant in the 4th U . S . Infantry on July 1 , 1831 . His service in the U . S Army consisted of several stints of garrison duty over the next three years , during which he was promoted to second lieutenant on September 15 , 1833 . McKean resigned from the U . S . Army the following year on March 31 . After resigning in 1834 , McKean took up work as a civil engineer . He then participated in the Seminole Wars in 1837 – 38 , serving as adjutant of the 1st Pennsylvania Volunteers , with the rank of first lieutenant . McKean resigned on March 31 , 1838 , and returned to Pennsylvania and the profession of an engineer . In 1840 he relocated to Marion in the Iowa Territory , and in 1844 he was part of the constitutional convention aimed at creating the state of Iowa . During the Mexican – American War , McKean volunteered for service , and enlisted as a private in the 15th U . S . Infantry on April 12 , 1847 . He was quickly promoted to sergeant major on May 10 , and fought in the Battle of Churubusco on August 20 , in which he was wounded . That June , McKean was appointed to the rank of brevet second lieutenant in the 2nd U . S . Dragoons , but he chose to decline the commission . After hostilities ended , he was discharged on August 7 , 1848 . Historian Ezra J . Warner noted McKean ' s unusual situation of having been trained at West Point and served in other duties as an officer , but was as an enlisted man in combat while in Mexico . Following the war he returned to his civilian life in Iowa , a U . S . state since 1846 . Civil War service . When the American Civil War began in 1861 , McKean chose to follow his home state and the Union cause . On June 1 he was appointed the paymaster of the Union Army , and then led the cavalry of the Department of the Gulf beginning on September 18 . McKean was briefly in charge of prisoner of war camps in Missouri , and was appointed a brigadier general in the Union Army on November 21 . McKean commanded at Jefferson City , Missouri , from December to March 1862 . He was then given divisional command in the Army of the Tennessee on April 10 . He fought in the Battle of Corinth in Mississippi on October 3 – 4 , and then led his division until December 9 . McKean then commanded numerous districts across Union - held departments throughout 1863 , 1864 , and until July 10 , 1865 . McKean was appointed to the rank of brevet major general on March 13 for his war service , and was mustered out of the volunteer service on August 24 . Postbellum . After the American Civil War ended in 1865 , McKean returned home to Iowa . He was elected Marion ' s mayor that year , and took up farming close to the city until 1869 . He served as a delegate to the Republican convention in Chicago , Illinois , in 1868 . McKean was offered the position of pension agent of the eastern Iowa district in early 1870 , but he declined it . That April he died in Marion , Iowa , and was buried in the city ' s Oak Shade Cemetery .