Spectacularly bald, with huge side-whiskers, Sam Carroll's nickname was "Old Brick Top" because of his red hair. He was fearless and vigorous, a brigade leader of a type rare in the Army of the Potomac--one who would attack "wherever [he] got a chance, and of [his] own accord." Eleventh Corps commander Maj. Gen. Oliver O. Howard described him in 1863 as being "a young man of quickness and dash" and added that "for fearless and energetic action Colonel Carroll had not a superior." He was admired not only by those who commanded him, but by those he commanded. One of his subordinates described him as "a thorough soldier and unsurpassed commander of men," and another remembered Carroll as "a splendid commander to lead a forlorn hope," for his voice was like the blast of a trumpet, and to hear it ordering a charge was "worth a whole regiment itself as a reinforcement."
Carroll had come from a prominent District of Columbia family; his father was for many years clerk of the Supreme Court. Young Sam had been sent to West Point, where he was a disaster as a student, graduating 44th out of 49 cadets in the class of 1856. After serving four years on the frontier, he returned as quartermaster to the Military Academy, where he and his family shared a double house with that of Howard. The families became close, so that when Howard became seriously ill in Washington in 1861, Carroll's mother took him into her home and nursed him back to health.
The Civil War began soon after, but Carroll was not released for field duty by West Point until the fall of 1861. By December 1861 Carroll had been made colonel of the 8th Ohio regiment, joining his command in Romney, West Virginia. He shined in his first battle, at Kernstown during the opening of the Jackson's Shenandoah Valley Campaign in March 1862, and was commended by both his brigadier and division commander Brig. Gen. James Shields after the battle. On the basis of his obvious ability and his performance at Kernstown, he was given command of a brigade in May, and on June 9 fought for the first time at the head of it at Port Republic, where the Union forces were defeated by Jackson. Afterwards, Shields sharply condemned Carroll's "blunders": "Colonel Carroll neglected to burn the bridge at Port Republic. . . . He held it three-quarters of an hour and wanted the good sense to burn it. They took up an indefensible position afterward instead of a defensible one." (Shields neglected to mention that five days earlier he had expressly ordered Carroll to "go forward at once with the cavalry and guns to save the bridge at Port Republic.") To add injury to insult, Carroll was hurt during the battle when his wounded horse fell on him.
Transferred to Pope's Army of Virginia in the summer of 1862, Carroll's brigade was only lightly engaged at Cedar Mountain on August 9. However, he was included in a short list of those praised by General John Pope after the battle. A week later, Carroll was wounded in a skirmish with Rebel cavalry while inspecting his pickets near the Rapidan River, receiving a painful flesh wound in the chest that incapacitated him for the next month and kept him out of the Battles of Second Bull Run and Antietam.
Recovering by late September, he was briefly assigned to the Washington defenses before returning to the field in time to command a Third Corps brigade at Fredericksburg. There, although Carroll's brigade was used only in support and never influenced the battle, Carroll was singled out for praise by division commander Brig. Gen. Amiel Whipple, who wrote of his "bravery and skill."
"Old Brick Top"--who wasn't old at all, only thirty years old at Gettysburg--requested in early 1863 that he and the 8th Ohio be transferred to the Second Corps. While he waited for the change of assignment, he went on sick leave--his lung was hemorrhaging from his wound of the previous summer, he suffered from an intermittent fever, and he had rheumatism in his left hip and knee. His request for transfer was granted on March 25, 1863. He returned to the army and took command of the veteran Second Corps brigade to which his regiment had been newly assigned, since its previous brigadier, Brig. Gen. Nathan Kimball, had been severely wounded by a canister ball in the thigh at Fredericksburg. Carroll commanded this brigade at Chancellorsville, where, after a fine performance in the confused May 3 fighting, division commander Maj. Gen. William French called special attention to him, calling him "dashing and gallant," in his official report of the battle.
It is interesting that, after leading brigades in the battles of Port Republic, Fredericksburg, and Chancellorsville, and especially after French's commendation for his performance in the latter battle, Sam Carroll was still commanding a brigade at the rank of colonel at Gettysburg. Perhaps his lack of promotion was due to the black mark of Shields's scathing report after Port Republic. Whatever the reason, it is certainly no credit to the promotional machinery of the Army of the Potomac that a man of Carroll's qualifications was still a colonel in the summer of 1863 when inferior men were wearing stars. Sam Carroll in the summer of 1863 was a West Point trained, veteran brigade commander. He had three months' familiarity with his present brigade. He was a man who possessed dash and gallantry, and his men liked to identify themselves as "Sam Carroll's Men," which says much about his leadership.
Posted just south Cemetery Hill upon arrival on the morning of July 2, Carroll listened to the battle in near the Round Tops draw closer all afternoon, but he wasn't called on until dark, when Early's division struck the Eleventh Corps lines on Cemetery Hill. Hearing the sounds of fighting there, Second Corps commander Maj. Gen. Winfield S. Hancock sent Carroll's brigade as a reinforcement. With no direction from above, Carroll managed to put his men exactly where they were most needed by marching toward the heaviest fire, and skillfully positioned his men for the attack in the dark. When Carroll's men charged, they were irresistible, and quickly pushed Hays's Louisianans back off the hill. After remaining for a while in a defensive line exposed in front of the other friendly troops there, Carroll sought permission to retire. His old friend Eleventh Corps commander Major General Howard refused to give it, feeling much safer with Carroll's than with his own men in the line, and Carroll and three of his regiments stayed to defend Cemetery Hill from the north.
Carroll left one regiment behind, his old 8th Ohio, and it would help turn back the left wing of Pickett's Charge the next day, firing into the flank of the attack as it neared the Union lines.
After the battle, Carroll's division commander, Brig. Gen. Alexander Hays, wrote, "Too much credit cannot be given to Carroll and his command for the gallant manner in which they went to the relief of the troops on our right." To his report of the battle Howard appended a personal "hearty thanks" to Carroll. "Old Brick Top" commanded his brigade through the fall campaign and retained command when the Army of the Potomac was reduced from five corps to three in March 1864. However, he still had not received a promotion to the proper rank of brigadier general when, on May 12, 1864, his arm was splintered by a bullet at Spotsylvania, putting him out of action for the rest of the war. He belatedly received his brigadier's star, effective from the date of his wound.