Gregg's brigade fought in the Battle of Jackson, Mississippi on 14 May 1863. Moody was badly wounded in July near Jackson, Mississippi and never returned to the regiment. The 7th Texas fought at the Battle of Chickamauga on 19–20 September, losing eight killed, 78 wounded, and one captured out of 177 men. Gregg's brigade, which formed part of Bushrod Johnson's division, suffered 109 killed, 474 wounded, and 18 missing, a total of 601 casualties. On the first day, Gregg's brigade became involved in a see-saw musketry duel with Hans Christian Heg's Federal brigade. Later, as Gregg's regiments were moving through the forest, they bumped into Charles Garrison Harker's Union brigade. In heavy woods, Gregg inadvertently rode into a Federal skirmish line and was shot down. After the skirmishers took his sword and spurs, some men from the nearby Texas Brigade rescued the unconscious general. Cyrus Sugg took command of Gregg's brigade. On the second day, James Longstreet placed Johnson's division at the forefront of his heavy column of attack. The 7th Texas formed the left flank of Johnson's first line. By an astonishing blunder, the opposing Union troops marched away, leaving a hole in their line. Johnson's division advanced into the gap, beginning the rout of the Union right wing. Later, when Sugg's brigade was striking toward the Union rear at Horseshoe Ridge, James B. Steedman's Union division fortuitously appeared and repulsed the Confederate attacks.