Its reputation increased when it spearheaded Longstreet's assault on Pope's left at the battle of Second Manassas. The brigade overran two Union regiments, nearly annihilated the 5th New York Zouaves, and captured a battery of guns, losing 628 men in the battle. Its reputation for fighting was sealed at the Battle of Sharpsburg, when it closed a gap in the Confederate line and drove back the two Union Corps that were attacking. Out of 854 that went into battle at Sharpsburg, 550 of the Texas Brigade were killed or wounded.