[3][4] Walthall was elected colonel of the 29th Mississippi Infantry on April 11, 1862, and fought at the Siege of Corinth and in the Confederate Heartland Offensive.

[1][3][4] Commanding one of the Army of Tennessee's brigades during November 1862 he was appointed brigadier general on December 13, 1862.

[1] Walthall led his brigade in the Tullahoma Campaign and fought at the Battle of Chickamauga on September 19–20, 1863.

[1][4] At the Battle of Franklin on November 30, 1864, Walthall was wounded (at least badly bruised) as he had two horses shot from under him, but he quickly returned to duty.

[5] Walthall was appointed as a Democrat to the U.S. Senate to fill the vacancy caused by the resignation of Lucius Q. C.

[5] Walthall was again elected for the term beginning March 4, 1895, and served from that date until his death in Washington, D.C., on April 21, 1898.