1. Confederate commander Braxton Bragg had fought near Chickamauga before.

Bragg, an 1837 graduate of West Point, was just 21 when he received his first military assignment, attached to the 3rd U.S. Artillery, first in Florida and then in Georgia and Tennessee. In 1838, Bragg was part of a unit tasked with rounding up members of the Cherokee tribe near Chattanooga and Chickamauga for settlement in the American West. More than 5,000 Cherokee died, primarily of disease and starvation, on the brutal 1,200-mile trek that became known as the Trail of Tears.

2. Future President James Garfield served at Chickamauga.

James Garfield joined the Union army in 1861, serving with distinction in Kentucky and at the Battles of Shiloh and Corinth. By September 1862, he had risen to the rank of brigadier general and was named chief-of-staff to General William Rosencrans. When the Union lines were breached at Chickamauga, Rosencrans and his staff tried to rally their troops, before retreating to Chattanooga. Just months later, Garfield—who had a been active in Republican politics in his native Ohio—was elected to the U.S. House of Representatives, despite the fact that he was still in the army and had not actually campaigned for the office. He resigned his commission to enter Congress, and in later years would dramatically play up the importance of his role at Chickamauga, often at the expense of former commander Rosencrans. Garfield was elected president in 1880, but was shot just four months after his inauguration. The president lingered on for almost three months before succumbing to his wounds on September 19, 1881—the 18th anniversary of the Battle of Chickamauga.

3. James Longstreet caught a lucky break.

On the second day of the battle, confusion reigned at Union headquarters, as limited vision in the thick woods around Chickamauga caused a scout to erroneously report that a Union division was out of position, leaving Rosencrans’ with a gap in his line. The scout’s report was incorrect; the division was there, but partially hidden by the forest. Unaware of the mistake, Rosencrans ordered one of his generals, Thomas Wood, to close the gap, which Wood begrudgingly did (he was aware of the lack of a gap). By doing so, however, Wood opened up a real hole in the line, which Confederate General James Longstreet immediately exploited, decimating the Union forces.

4. New weapons played a key role in the battle.

Three months before the Battle of Chickamauga, Union Colonel John T. Wilder had garnered wide praise for his decisive role in the Union victory at Tullahoma, Tennessee. Crucial to Wilder’s success had been the newly introduced Spencer repeating rifles, capable of firing up to 20 rounds per minute, more than twice the speed of traditional firearms. Wilder and his well-armed men of the 17th Indiana Infantry Regiment saw action again on September 18, 1863, when they fought off approaching Confederate troops on the eve of Chickamauga. An on the battle’s second day, his mounted infantry was one of the only Union regiments to withstand James Longstreet’s assault and attempt a counterassault. Longstreet was so surprised by the barrage of firepower laid down by Wilder’s “Lightning Brigade” that he mistakenly believed a fresh group of Union reinforcements had arrived.

5. Union Major General George H. Thomas earned the nickname the “Rock of Chickamauga” after the battle.

The Virginia-born Thomas was a veteran of the Seminole and Mexican-American Wars and had served alongside Robert E. Lee and other future Confederate adversaries in Mexico before the outbreak of the Civil War. Choosing to stay loyal to the Union, he saw action at Corinth, Perryville and Stones River and was once offered command of the Army of the Ohio (soon renamed the Army of the Cumberland)—a post he refused. Serving under the Cumberland’s new commander, William Rosencrans, Thomas led the XIV Corps at Chickamauga, successfully (but temporarily) holding his line against the Confederate onslaught on Horseshoe Ridge and preventing a complete Union rout. It was reportedly Rosencrans’ chief-of-staff, James Garfield, who noted Thomas’ bravery, stating that the officer was “standing like a rock” in the face of certain defeat. The nickname stuck, and Ulysses S. Grant chose Thomas as Rosencrans’ successor at the helm of the Cumberland soon after.

6. The South won the battle, but Chickamauga is often referred to as the “death-knell” of the Confederacy.

Bragg’s decisive victory at Chickamauga came at a high cost, with more than 20 percent of his forces killed or wounded, including 10 generals. Instead of pressing his advantage after the victory, Bragg allowed the Federals to safely reach Chattanooga, intending to secure the heights around the city and lay siege to Union forces. When Ulysses S. Grant’s reinforcements arrived that fall, they drove the Confederates from the region. With Chattanooga secure, Sherman used the city as a base for his campaign against Atlanta in 1864.

7. It was the first National Military Park.

Thanks to the efforts of two Chickamauga veterans who had served in the Union army, a portion of the lands that saw fierce fighting in both that battle and the later clash at Chattanooga, were used to create the first National Military Park (NMP) in the United States. Officially opened in 1895, it served as the model for all future military parks, including those at Gettysburg, Shiloh and Vicksburg. Today, the Chickamauga and Chattanooga NMP is comprised of more than 9,000 acres and receives nearly 1 million visitors annually.

8. Chickamauga was used by the U.S. military long after the Civil War.

Thanks to its strategic location at the junction of several rail lines, the battlefield at Chickamauga remained an important location for the U.S. army for more decades. In 1898, as conflict between Spain and the United States heated up, the grounds were used as a training site for soldiers, with more than 60,000 men passing through the site, which was temporarily renamed “Camp George H. Thomas.” A summer heat wave combined with hastily assembled facilities resulted in unhealthy conditions in the camp, and when a deadly typhoid epidemic it killed approximately 400 men—more than the total combat deaths the United States would suffer in the subsequent Spanish-American War.