Moving north from Georgia's West Point, John Bell Hood planned to attack General William Tecumseh Sherman's supply line, the Western and Atlantic Railroad. Moving north through western Cobb County and avoiding Sherman's stronghold at Kennesaw Mountain, Hood ordered A. P. Stewart to attack a series of blockhouses and Union encampments near the railroad on October 3, 1864. Hood then issued orders to General Samuel French to advance to Allatoona Pass and attack the entrenched Union force within a star fort on top of mountain overlooking a train pass carved out of dirt and stone. In one of Hood's most bizarre orders of his career, he told French to march to the pass, attack the fort, fill the 185 foot deep pass with earth and logs, then meet Hood's army further north in 36 hours.

As Hood came out from the dense undergrowth near Lost Mountain, Sherman signaled John Corse in Rome to move to Allatoona and assume command of the outpost. Corse was a good choice to command the fort, at least as far as Sherman was concerned; he is quoted as saying "I know Corse. As long as he's alive, Allatoona Pass is safe."

Positioning men to the attack from the north and the west, French wisely chose to advance along a ridge to a small redoubt west of the star fort, then advance to the fort itself. Fighting at the outer redoubt was extremely heavy and by the time the 93rd Illinois withdrew to the fort both it and French's army had sustained a majority of the casualties for the battle.

Rebels in the valley in front of the fort moved up the hill, challenging but never breaching a Union line of entrenchments on either side of the hill. Inside the fort, Union soldiers who stood up would be picked off by sharpshooters positioned on nearby ridges that were slightly higher. Resupplied by a one-man bridge across the pass, the fort continued to fight until French broke off the engagement when signals from Kennesaw indicated that a Union force was on its way.

With none of his major objectives met, French attacked a nearby blockhouse, then returned to the main body of Hood's force and continued north.

Based on the ratio of men committed to battle to the casualties, Allatoona Pass was the bloodiest battle of the Civil War.

Maj. Gen. Wm. T. Sherman

Brig. Gen. John M. Crose

Maj. Gen. Samuel G. French

Maj. Gen. John B. Hood