Had George McClellan been the military genius Melville hails him as in this poem, the War might well have ended on the banks of Antietam Creek on September 17, 1862. Instead, McClellan frittered away numerous opportunities to rout the Army of Northern Virginia despite finding an errant copy of Robert E. Lee's Special Order No. 191 outlining Confederate strategy for the upcoming campaign.
After McClellan floundered badly on the Peninsula in July, the Army of the Potomac was removed from his command a piece at a time, and he was forced to watch from the sidelines as General John Pope bungled the Battle of Second Manassas. The AoP was subsequently reconsolidated under "Little Mac" even though Abraham Lincoln had grave misgivings about his demonstrated unwillingness to bring the army to battle.
Federal troops outnumbered the Confederates by a considerable margin at the Battle of Antietam, but McClellan was exceedingly cautious about commiting his men, in many cases refusing to send them where their presence was sorely needed "in case" something should happen elsewhere on the field. Far from "fighting in the front," as the poet says, McClellan watched the battle unfold from the safety of his hilltop headquarters at the Pry house, some distance from the field.
Although McClellan's army inflicted heavy casualties on the Army of Northern Virginia on the 17th, Lee did not withdraw immediately, believing until the last minute that a counterattack was possible. On September 18, the ANV slipped across the Potomac under cover of darkness and back to the safety of Virginia. McClellan lost yet another golden opportunity to destroy Lee's army by believing his own army too badly crippled to give pursuit.
If Lee had failed to gain the hoped-for foothold in the North, McClellan had failed to destroy the ANV or to win a decisive victory. Still, the quasi-triumph gave the Union the boost that President Lincoln needed to issue the Emancipation Proclamation on September 22.
McClellan's failure to follow up on whatever advantage the North might have gained at Antietam was the final nail in his coffin -- and Lincoln was only too happy to pound it in, relieving McClellan of all command responsibilities after the AoP did nothing in seven weeks of prime campaigning season following the battle. The general retired to private life and ran against his former commander in chief for president on the Democratic ticket in 1864 -- and lost.
"The Victor of Antietam"