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High Stakes at Antietam
A largely accidental battle, pitting Robert E. Lee against George B. McClellan, became the single deadliest day in America's history and changed the course of the Civil War.
Summer 2012 | Volume 62, Issue 2
Lee sent in John Bell Hood’s division in a counterattack that drove back Hooker’s corps. Hooker countered with Mansfield’s Twelfth Corps, and although General Mansfield fell mortally wounded, his corps, now under Alpheus Williams, gained a foothold at the Dunker church and achieved a momentary stalemate on this northern battlefront. McClellan had assured Hooker that the rest of the army would attack in concert with him, yet he did not call up General Edwin Sumner’s powerful Second Corps to reinforce the attack for nearly two hours. When the order finally came, Sumner had two miles to march to reach the fighting.
General Sumner was 65, a gallant old warrior but, as McClellan put it, “nature had limited his capacity to a very narrow extent.” McClellan intended him to arrive as support for the attack and thus be under Hooker’s direction, but Hooker fell wounded, and abruptly Sumner was in command of the northern front. McClellan held back the third of Sumner’s three divisions to bolster his defenses against the counterstroke he expected from the Confederate host, and the second of Sumner’s divisions lagged behind and wandered off course. With only a single division, led by General John Sedgwick, but determined to turn the enemy’s flank, Sumner marched in three lines of battle straight into the West Woods.
General Williams of the Twelfth Corps warned that the enemy was in force in the West Woods, but Sumner brushed off the warning, and Williams watched horrified as Sedgwick’s division “made, without halt or reconnaissance, straight for the woods.” Lee, in a perfect reading of the battlefield, had ordered one of his divisions just up from Harpers Ferry to reinforce Jackson, and with explosive force it slammed into the left flank of the Federal advance.
Sedgwick’s three brigade lines were hardly 50 yards apart and unable to pivot to meet the assault. In moments 600 men fell, and the lines crumpled like rows of dominoes. A Massachusetts soldier reported that “the left Regiments gave way in confusion, the enemy poured in upon our rear, and now the slaughter was worse than anything I have ever seen before.” The rout in the West Woods ultimately cost the Federals over 2,300 casualties and all but ended the fighting on the northern battlefront.
The Second Corps division that had gone astray stumbled into a new battlefront at Lee’s center. The Confederate line here followed a farm lane that erosion and travel had worn down to form a natural trench, to be known as the Sunken Road. The Federal commander, unimaginative William H. French, could think of nothing better than serial frontal attacks against the Sunken Road position. A North Carolina colonel said his volleys “brought down the enemy as grain falls before a reaper.” McClellan finally released Israel Richardson’s Second Corps division, which joined French in the assault. Lee threw in his last reserves to brace his endangered center.
Richardson’s forces overlapped the enemy line, and suddenly the Sunken Road became a death trap for its defenders. Lee’s center fell into collapse, held only by a line of guns. Richardson called for reinforcements, especially in artillery, but his call went unanswered. Then he was mortally wounded, and his fall marked the end of the fight for the center. McClellan, blind to opportunity, was content to stand on the defensive. Lee was reprieved.
Lee was soon reprieved a second time when McClellan rode to the right to consult with his generals. The Sixth Corps had now reached the field, and its commander, William Franklin, proposed leading a renewed battle there. But old Sumner was demoralized, insisting that any further fighting on this front would risk “a total defeat.” McClellan would not overrule him, saying he “was afraid to risk the day by an attack there on the right at this time.”
“Afraid to risk”—the epigraph for George McClellan’s generalship.
One act remained before darkness ended the fighting. Ambrose Burnside, at the southern end of the field, was the only Federal general that day to face a contested Antietam crossing. On the west the ground fell steeply to the creek bank, and the Confederate defenders had the narrow stone bridge there under point-blank fire. It took three hours and three costly attacks before the bridge was taken. But by afternoon the Ninth Corps was advancing steadily on Sharpsburg and threatening Lee’s sole line of retreat. Then came a devastating surprise—A. P. Hill’s division, the final piece of Lee’s army, arriving after a hard march from Harpers Ferry, crashed into Burnside’s flank and drove his command back to the bridge. The surprise stemmed from one of McClellan’s more egregious errors of the day: He massed his cavalry behind his center, leaving the army’s flanks unguarded, so that Hill’s attack seemingly came out of nowhere.
September 18 found Lee standing defiantly in his lines and McClellan making no move to resume the battle, and that night the Army of Northern Virginia crossed the Potomac back into Virginia. The Federals’ modest attempt at pursuit was hurled back by Lee’s rear guard. McClellan announced that Maryland and Pennsylvania were safe from the invaders and credited himself with a great victory against long odds. But in truth he had not fought to win, only to avoid losing (he engaged only 11 of his 17 divisions), and consequently Robert E. Lee escaped a potentially crushing defeat. Soldier-historian Ezra Carman wrote of Antietam: “History will not accept [McClellan’s] view of the battle, in the conduct of which more errors were committed by the Union commander than in any other battle of the war.”