American history’s bloodiest day

James M. McPherson is America’s preeminent Civil War historian. His new book tells the story of one violent day when the whole American future was up for grabs. Had that day ended differently, had the Confederate Army prevailed at the Battle of Antietam, the history that we know would never have come to be. Another future, one we can only imagine, would have followed.

Imagine this: The Confederacy would have probably won independence -- a new nation dedicated to the proposition that some people are created slaves -- and America’s revolutionary experiment to determine whether ordinary people can govern themselves would have been fatally discredited. There would have been two antagonistic nation states between Canada and Mexico. Other wars between the North and the South would have been inevitable. The rivalry would have precluded the rise of a continental American republic as a great world power, eventually the great world power. What then would have been the prospects of defeating the murderous totalitarian regimes of the 20th century? In McPherson’s hands, the Battle of Antietam gains an urgent immediacy, because his brief narrative is driven by an awareness of the element of contingency, the “what if” of history. By showing how Antietam changed the course of the Civil War, “Crossroads of Freedom” suggests how the outcome may have shaped world history.

McPherson describes the fighting itself in no more than 20 pages, but few who read those pages are likely to forget them. The most harrowing passages force us to confront the physical reality of war. Antietam furnished scenes of such horror that veteran officers were reduced to mute, incontinent children. Storms of projectiles left men holed and punctured, shattered into fragments, beheaded and disemboweled. Those left standing spoke of “hundreds of dead bodies lying in rows and in piles.” There were mires of congealed blood, heaps of “vomit and excrement,” an “insupportable” stink of rotting flesh and the abominable sight of hogs and maggots feasting on soldiers’ corpses. A year later, the fields were still strewn with bones. For years to come there would remain the hobbling, crippled survivors, and enduring desolation in thousands of hearts. About 6,500 American soldiers died at Antietam. An additional 15,000 were wounded. Sept. 17, 1862, remains the bloodiest single day in the nation’s history. Those killed at Antietam outnumber the dead of Pearl Harbor and D-day combined.

All the bloodshed at Antietam would have been little more than a ghastly exhibition of human ferocity had not the American Civil War been imbued with a higher purpose: the emancipation of 4 million slaves. “Without slavery the rebellion could never have existed; without slavery it could not continue,” Abraham Lincoln said. No one doubted that in the 1860s, though many have tried to deny it since. The irony is that, during the first year of the war, both the North and South fought to preserve slavery. While it is clear that the Confederacy fought for national independence as a new slave empire, it is sometimes forgotten that in 1862 the North’s war aims still did not include a policy as radical as the abolition of slavery. For the first year and a half of the Civil War, the North fought merely to restore the “Union as it was,” the union of free and slave states that had existed since the founding. No one then knew that in July 1862, President Lincoln had already decided to free all the enslaved people in the rebelling states if the Confederates did not lay down their arms before the end of the year. “We must free the slaves or be ourselves subdued,” he told his Cabinet. But his advisors persuaded him that the stroke against slavery must not fall when Northern armies were on the run. Emancipation at such a time would come as an admission of desperation. It would seem, said Secretary of State William H. Seward, like “the last measure of an exhausted government, a cry for help ... our last shriek, on the retreat.” And so, McPherson writes, Lincoln “put the proclamation away to wait for military victory. It would prove to be a long, dismal wait.”

But by September 1862, the Union’s survival was very much in doubt. Never had Confederate prospects looked brighter. An aura of invincibility kept company with Gen. Robert E. Lee’s hard-bitten soldiers as they waded across the Potomac River into Maryland in the first Confederate invasion of the North. For the last three months, the rebels had whipped the Yankees time after time. They were sure they could do it again -- this time on Union soil -- and their confidence was bolstered by the knowledge that one more Southern victory would almost surely make it impossible for Lincoln to win, or even to continue, his war to save the Union.

The South was hoping for diplomatic recognition of the Confederacy by Britain and France, which would not only bring European aid into their coffers but also provoke hostilities between the United States and Britain. A Southern victory would also provide the already robust antiwar and pro-Confederate faction in the North a significant boost. McPherson quotes Confederate Secretary of State Judah P. Benjamin’s prediction that “our recognition would be the signal for the immediate organization of a large and influential party in the Northern States favorable to putting an end to the war.” Benjamin was wrong only if he supposed that such a party was not already flourishing. There were many in the free states who had opposed the war from the start. Each fresh defeat swelled their strength. It looked like the Democrats would seize control of Congress in the midterm elections and compel the president to begin peace talks with the Confederates. That would mean Southern independence.

Lee crossed into Maryland, just days after giving the North another humiliating beating at the Battle of Second Manassas. The demoralized Union army had no choice but to face its formidable foes again. Commanding for the Union was Gen. George B. McClellan, surely one the most exasperating figures in all American history. McClellan was a military genius crippled by a curious mixture of megalomaniacal self-confidence and native cowardice. Lincoln had decided that McClellan “has the slows.” Almost as succinctly, McPherson presents “McClellan in a nutshell -- he would take no initiative without ‘absolute assurance of success’ -- which rarely if ever exists in any human endeavor, much less in war.” Through an extraordinary stroke of luck, a Union soldier stumbled on a copy of Lee’s secret plans for the Maryland campaign. McClellan learned that the Confederate Army was divided and vulnerable to attack in detail. A bolder commander would have used the intelligence to destroy Lee’s army. But McClellan, true to character, vacillated and threw away a shot at ending the war. Lee was able to bring his forces together before the headlong collision of the two armies.

Antietam was, nonetheless, a strategic victory for the North. The war would drag on for another 2 1/2 years, but the last best hope for Confederate independence had vanished with the gun smoke. The North’s victory was all the more commanding because it was so unexpected. The Army of the Potomac had stopped the Army of Northern Virginia cold and sent it reeling back to Virginia, nearly one-third of its troops dead, wounded or prisoners.

McPherson’s book represents a trend that many readers are sure to welcome: Some of our finest historians have taken to writing very short books. Gordon Wood has traced the entire era of the American Revolution, 1763 to 1789, in a half-inch-thick volume with just 160 pages of text. Edmund Morgan has captured Benjamin Franklin in a 300-page biography. Now, McPherson has demonstrated that he needs only 150 pages of narrative to describe the war’s most critical turning point and, in so doing, to illuminate the true meaning of the vast struggle between freedom and slavery.

“Crossroads of Freedom: Antietam” is the latest installment in the new Oxford University Press series “Pivotal Moments in American History.” The purpose of the series is to invite us to ask how history might have diverged from its familiar path. “The victory at Antietam could have been more decisive,” McPherson writes. “But Union armies had stymied the supreme Confederate efforts.... Foreign powers backed away from intervention.... Lincoln issued his Emancipation Proclamation. Northern voters chastised but did not overthrow the Republican party, which forged ahead with its program to preserve the Union and give it a new birth of freedom. ... Here indeed was a pivotal moment.”