In the Civil War, George Henry Thomas (1816-1870), U.S. Army officer, received the sobriquet "Rock of Chickamauga" for saving a Union army.

George H. Thomas was born on July 31, 1816, in Southampton County, Va. He graduated from the county academy and read law before attending the U.S. Military Academy (1836-1840). In Florida he won a brevet to first lieutenant during 2 years of action with the 3d Artillery against the Seminole Indians. He served at Southern posts until the Mexican War, in which he became a major after battles at Monterrey and Buena Vista. He was an instructor from 1851 to 1854 at West Point; in 1852 he married Frances Kellogg. He was major of the 2d Cavalry on the Texas frontier from 1855 to 1860.

At the beginning of the Civil War, Thomas decided to remain with the Union and by June had been promoted to colonel, in command of a brigade...