Alexander McDowell McCook was the highest ranking officer of the “Fighting McCooks”, fourteen members of one family who all participated in the Civil War. He graduated from the United States Military Academy in 1852 after taking five years to finish a four year program. He was posted to the 3rd Infantry and spent several years fighting Indians in New Mexico before returning to West Point to teach.
After the outbreak of the Civil War, McCook was commissioned as a colonel of the 1st Ohio Volunteers, and first saw combat during the First Battle of Manassas. On September 3, 1861 McCook was promoted to brigadier general, and was sent to Tennessee to command the 2nd Division of the Army of Ohio under General D. C. Buell. McCook commanded his men during the capture of Nashville, at the Battle of Shiloh, and during the Siege of Corinth. On July 17, 1863 McCook was promoted to major general for his actions in Tennessee. He was given command of the I Corps of the Army of the Ohio, and commanded them at the Battle of Perryville, where his corps suffered heavy losses. His command was reorganized into the XIV Corps of the Army of the Cumberland, and he suffered heavy losses at the Battle of Stones River. The army was again reorganized into the XX Corps, and McCook commanded the corps during the Union disaster at the Battle of Chickamauga. McCook and Union general T.L. Crittenden were blamed for the defeat at Chickamauga. He received a court-martial hearing for his actions at the battle, but was not found guilty of any wrong-doing. McCook was, however, relieved of command. He did not receive orders again until Confederate General Jubal Early threatened Washington, DC. McCook was placed in charge of defense forces around the capital, and commanded his men during the Battle of Fort Stevens.