Alexander McDowell McCook Alexander McDowell McCook ( April 22 , 1831 – June 12 , 1903 ) was a career United States Army officer and a Union general in the American Civil War . Early life . McCook was born in Columbiana County , Ohio . His family was prominent in army service — his father Daniel and seven of Alexander ' s brothers , plus five of his first cousins , fought in the war . They were known as " The Fighting McCooks " , for whom McCook Field in Dayton , Ohio , was named . His brothers Daniel McCook , Jr . , Edwin S . McCook , and Robert L . McCook were all Union generals , as were his cousins Anson G . McCook and Edward M . McCook . McCook graduated from the United States Military Academy in 1852 , served against the Apaches and Utes in New Mexico in 1853 – 57 , and was assistant instructor of infantry tactics at the military academy in 1858 – 61 . Civil War . At the start of the Civil War , McCook was appointed colonel of the 1st Ohio Infantry in April 1861 . He served in the Washington defenses and saw action at the First Battle of Bull Run . On September 3 , 1861 , he was promoted to brigadier general of volunteers and commanded a division in Tennessee . He earned the brevet of lieutenant colonel in the regular army for his part in the capture of Nashville , Tennessee . McCook then commanded the 2nd Division in the Army of the Ohio at the Battle of Shiloh on the second day of fighting , and then in the subsequent campaign against Corinth . He was promoted to major general of volunteers on July 17 , 1862 . McCook was given command of the I Corps in the Army of the Ohio . His corps suffered heavy casualties and driven back a mile at the Battle of Perryville in October 1862 . Command of the Army of the Ohio was reorganized and his command designated the Right Wing of the XIV Corps in the new Army of the Cumberland . His command again suffered heavy losses at the Battle of Stones River . Once again the command structure was reorganized and his corps named the XX Corps . For the third and final time , at Chickamauga , McCook ' s troops suffered heavily and were driven from the field . He was courtmartialed and partially blamed for the Union disaster at Chickamauga . He was not convicted but relieved of duty in the Army of the Cumberland . He waited almost a year before receiving another command assignment of any kind . It came thanks in part to Confederate General Jubal Early and his threat against Washington , D . C . McCook was placed in command of the " Defenses of the Potomac River and Washington " and was in charge of all forces defending the capital at the Battle of Fort Stevens . The day the battle ended , so did McCook ' s command of the city ' s defenses and he was again without command . At the close of the war he was given command of the District of Eastern Arkansas . He received brevet promotions to brigadier general and major general in the regular army for service throughout the war . Postbellum career . McCook resigned from the volunteer service in October 1865 and was commissioned lieutenant colonel of the 26th Infantry in March 1867 . He served in Texas , mostly in garrison duty , until 1874 . From 1875 to 1880 , he served as the aide - de - camp to the general - in - chief of the U . S . Army , Gen . William T . Sherman . From 1886 to 1890 ( except for brief terms of absence ) , he commanded Fort Leavenworth , Kansas , and the infantry and cavalry school there . McCook became a full brigadier general in 1890 , a major general in 1894 , and retired in 1895 . In 1898 – 99 , he served on a commission to investigate the United States Department of War as administered during the Spanish - American War . Alexander McDowell McCook died in Dayton , Ohio , and is buried in Spring Grove Cemetery , Cincinnati , Ohio . The town of McCook , Nebraska , was named in his honor .