The cadaverous Jackson, pale and weak from the loss of blood from a bullet wound in his shoulder suffered in a barroom gunfight, took command of the West Tennessee army.

From The Battle of New Orleans: Andrew Jackson and America's First Military Victory by Robert V. Remini.  Page 10.

At noon on August 30, 1813, the Red Sticks, led by a new recruit, William Weatherford (Chief Red Eagle), counterattacked. They entered through an open gate, slaughtered the defenders, and burned the fort. It was one of the most appalling massacres in frontier history. “The fearful shrieks of women and children put to death in ways as horrible as Indian barbarity could invent” echoed around the fort. The victims were “butchered in the quickest manner, and blood and brains bespattered the whole earth. The children were seized by the legs, and killed by batting their heads against the stockading. The women were scalped, and those who were pregnant were opened, while they were alive and the embryo infants let out of the womb.” Red Eagle tried to stop this savagery, but many red clubs were raised over his head and he was forced to withdraw to save his own life. Between 250 and 275 white settlers, friendly Indians, and mixed-bloods were killed; between twenty and forty escaped.

The horror of the massacre at Fort Mims, the savagery and audaciousness of it, rolled over the western country of America like a shock wave. Anger and fear and a demand for revenge ricocheted up and down the frontier. The governor of Tennessee, Willie Blount, responded immediately to the outcry. Empowered by the legislature to raise five thousand men for a three-month tour of duty, he ordered Major General Andrew Jackson of the Tennessee militia to “call out organize rendezvous and march without delay” 2,500 volunteers and militia “to repel an approaching invasion . . . and to afford aid and relief to the suffering citizens of the Mississippi Territory.”

On October 7, 1813, although pale and weak from the loss of blood from a bullet wound in his shoulder suffered in a barroom gunfight with Jesse and Thomas Hart Benton, and with his left arm in a sling, the six-foot-tall, cadaverous Jackson took command of the West Tennessee army at Fayetteville. His complexion was sallow and rather unhealthy-looking; nonetheless, the rest of his overall appearance exuded strength, if not fierceness. He always carried himself very erect, and his manner radiated confidence and sureness of command. He was forty-six years old and his steely blue eyes invariably registered his thoughts and feelings. At one instant they could blaze with anger and fury, at another with gentleness and understanding. Because of his strength and toughness as well as his constant attention to the welfare of his army, his soldiers affectionately called him Old Hickory. Hickory was as tough a substance as they knew, and General Andrew Jackson was, in their minds, indomitable.