Gettysburg is usually referred to as the "high tide" of the Confederacy. After Antietam, the South still has resounding victories in East at Fredericksburg and Chancellorsville in front of them. If anything, the early morning of September 17th was the high tide of slavery, and the horrible events of that day eventually ended the institution once and for all. This is a battle worth remembering for many reasons.

The period from Lee’s assumption of field command (and the offensive) in late May 1862 and Lincoln’s issuance of the Emancipation Proclamation on New Year’s Day 1863 appears to me to have been THE hinge period par excellence of the Civil War.

And Antietam was "the hinge of the hinge" during this phase that also saw Jackson’s Valley Campaign, the Seven Days’ Battles, Second Bull Run, Perryville, Fredericksburg, and Stone’s River.

I know some would nominate as turning points Gettysburg (the biggest land battle ever in the Western Hemisphere) or Sherman’s seizure of Atlanta (which secured Lincoln’s reelection after a very hairy spring and summer of 1864 for the North).

Here’s why I vote for Antietam:

The phase of which Antietam is the crux event saw the war transformed from a struggle to restore the Union on more or less the old terms including probably a modus vivendi with slavery to a truly ’revolutionary’ war to complete the work of the Founding and destroy slavery once and for all. (Gen. McClellan was an "old terms" man, btw, and had probably conceived the Peninsular Campaign whose failure marked the beginning of this period in hopes of forcing a quick end to the war BEFORE it could become a wide-ranging fight to remake major aspects of American society.)

Antietam made emancipation politically possible. Lincoln’s announcement of freedom for slaves (even in its first, limited form) in turn effectively foreclosed the Southern hope that England (and following London’s lead, France) would enter on the side of the CSA.

Southerners openly spoke of the Confederate project as "the Second American Revolution," and as in the first the intervention of a European power was supposed to tip the balance. A major victory on Northern soil that would swing the crucial border state of Maryland to the Southern cause was supposed to help in this effort. Antietam frustrated this Confederate plan and made it possible for crushing slavery to become a non-negotiable Union war aim.

For these reasons, I nominate Antietam, tactical draw though it was, as the strategically most important battle of the war.

An afterthought: The CSA in the fall of 62 also expected its incursions to rally both slaveholding Kentucky and slaveholding Maryland to the Southern cause, but in neither case did this happen, nor was it about to. Reflecting on this, I would suggest, should lead one to downrate somewhat the significance of the Gettysburg campaign, since the first invasion of the North had already demonstrated that any further crossings of the Potomac would face limited strategic opportunities and indeed would resemble punitive or foraging expeditions rather than potentially war-winning demarches with a potential to split the North and bring foreign powers in to the help the Confederacy.

Antietam meant an end to slavery once and for all, and no European intevention. Epochmaking.

Is there something poetically fitting about the fact (if I am right) that the Civil War’s single bloodiest day was also its most strategically and politically crucial?

I agree with you on every point but one: That the Gettysburg campaign was doomed from the start to be anything but a punitive or foraging expedition. The campaign presented a very real strategic and political opportunity for a swift conclusion to the war. Lee was one afternoon, or one countermarch, or one timely attack on Cemetery Hill away from achieving a truly devestating blow to Lincoln and the Union. But, such is war, and I certainly can’t say that a victory was any more likely than a defeat. By all means, it was a long shot - but the Confederate strategy for the duration of the war was, by necessity, formed on very long shots. Having said this, I have long thought that Gettysburg has been overrated as the "turning point". There is much merit to the idea that the Maryland campaign was the true decisive point - culminating in the purely military Emancipation Proclamation. Interesting and important stuff, regardless.

Thanks for your comment.

You’re right to point out that there were a number of close-run episodes in the East even after Antietam, to be sure.

On the 2nd day at Gettysburg, more alert CSA commanders on the spot might have driven just a stone’s throw around lower Culp’s Hill on the extreme Union right and pitched straight into the Baltimore Pike, the main artery into Meade’s center rear on Cemetery Ridge. The fighting on Culp’s Hill has been obscured by all the attention paid to Lawrence & the 20th Maine at the other end of the line, but it was just as dramatic, to my mind, and just as easily if not more easily could have turned the battle.

Had Jubal Early reconnoitred and maneuvered more energetically against the scratch Union force facing him at the Monocacy River crossings south of Frederick, Md., on July 9, 1864, he might have reached Washington and driven into the city before the reinforcements that Grant was sending north could get there. What effect that might have had on the war we cannot say, of course, but one may well imagine that it would have been more than trivial.

And of course at Antietam itself, the charge of Hawkins’s USA Zouaves in the afternoon south of Sharpsburg came literally within minutes of cutting the Harper’s Ferry Road. AP Hill really did show up in just the nick of time (something similar in the way of close shaves happened at Laurel Hill on the Spotsylvania battlefield on May 8, 1864).

And in the West, of course, there’s the amazing lost Confederate opportunity at Chickamauga in Sept 1863. I believe that battle was truly the closest the CSA ever came to actually destroying a major Union field army as a meaningful fighting force (something Lee tried to do repeatedly, but never really came close to, not even at Chancellorsville, with the possible exception of the final phase of Second Bull Run, when only the stand of the US Regulars at Henry House Hill prevented Pope’s retreat from becoming a wild full-on rout). But Chickamauga was not followed up and Grant arrived to reverse the strategic picture completely, giving us Civil War buffs yet another counterfactual to kick around.

ya big nerds