The Union victory at the Battle of Antietam, one of the bloodiest encounters in American history, was a pivotal moment in the Civil War. Although General George McClellan did not draw on his ample reserve forces to smash Robert E. Lee’s Army of Northern Virginia nor did he pursue his adversary across the Potomac, the battle ended the Confederacy’s invasion of the North, helped the Republican Party retain its majorities in the House of Representatives and the Senate in the 1862 elections, and discouraged Britain and France from recognizing the Confederacy. Antietam also allowed President Lincoln to issue the Emancipation Proclamation, freeing the slaves in the secessionist states (without appearing to have done so out of desperation).

In “The Long Road to Antietam,’’ Richard Slotkin, professor emeritus of English at Wesleyan University, provides an engrossing minute-by-minute narrative of the battle. More importantly, in a fresh interpretation, he reminds us that the context for the tactical decisions was a struggle between Lincoln and McClellan, whose outcome was by no means certain, over whether the war would be accompanied by a political revolution. After Antietam, Slotkin argues, it was clear that there would be no compromise settlement between the North and South. The struggle became a “total war,” putting civilians as well as soldiers in harm’s way.

"Long Road to Antietam" by Richard Slotkin

Slotkin endorses the conventional wisdom among historians about McClellan’s strengths and weakness as a military man. A superb organizer, trainer, and motivator, he was extremely popular with Union troops. But he tended to overestimate the forces arrayed against him and moved far too cautiously in seizing opportunities to attack.

Equally important, according to Slotkin, McClellan had an inflated sense of himself, was an execrable judge of character, thought the president was a fool who should defer to him in military matters, and remained convinced (along with many Northern Democrats) that the best path to reunion involved the conciliation of Southern slaveholders.

At Antietam, Slotkin suggests, McClellan decided that he could end the Civil War and burnish his reputation as the nation’s most indispensable man by forcing Lee to retreat — and that it was unwise to risk disastrous defeat (or a victory that would enhance the power of the Radical Republicans) with an all-out assault.

The situation was further complicated, Slotkin reveals, because rumors were rife around the country about an imminent military coup. Newspaper editors, politicians, members of McClellan’s staff, and McClellan himself speculated about the Army forcing the government to negotiate a peace treaty that would include some form of Southern independence. Even if these threats were just talk, Slotkin implies, Lincoln understood that a public confrontation of McClellan, let alone sacking the general, could provoke a constitutional crisis or undermine his authority as president.

In the end, as McClellan resumed his stationary or slow-motion offensive against Lee, the president did relieve him of command, replacing him with Ambrose Burnside. Much to the surprise of French officers attached to his headquarters as observers and the chagrin of Union soldiers, who urged him to disobey orders, McClellan responded with a decidedly non-Napoleonic passivity. Conversations with civilian and military colleagues may have convinced him that the American people would not countenance a coup. Perhaps as well, Slotkin suggests, “a decision so bold was simply beyond him.”

On the day before he boarded the train to return to Washington, awaiting further orders that never came, however, a speaker at a rally in New York called for the nomination of McClellan as the Democratic candidate for president in 1864. The not-so-old soldier was not yet ready to fade away.

Lincoln would prevail, of course, against the Confederacy and in his decidedly uncivil war with General McClellan. But, Richard Slotkin concludes, it was a perilously close call.