Alexandra Petri writes for The Post’s humor blog, ComPost.

The battle over the meaning of Gettysburg has been going on for 150 years.

For Abraham Lincoln, speaking over the dead on Nov. 19, 1863, the power of the men’s sacrifice lay in the “cause for which they gave the last full measure of devotion”: preserving the union and enabling “a new birth of freedom” encompassing all men.

For Edward Everett, whose less memorable and rather less succinct remarks preceded Lincoln’s that day, Gettysburg was about the union, sure, but it was also a signal military triumph, a victory for the ages whose landmarks and battle incidents would assuredly form the study of future generations. “Seminary Ridge, the Peach Orchard, Cemetery, Culp, and Wolf Hill, Round Top, Little Round Top, humble names, henceforward dear and famous — no lapse of time, no distance of space, shall cause you to be forgotten. . . . In the glorious annals of our common country, there will be no brighter page than that which relates the Battles of Gettysburg,” Everett declared at the end of an oration lasting two hours.

Many other voices have since added their estimates of Gettysburg to the balance. But the debate persists: Did the battle’s meaning lie on the field, or beyond it? Was the primary importance of those three days of bloody fighting to offer Lincoln a venue for rhetorically redefining the war? Does it matter if we remember what was said there (or at least what Lincoln said there) more clearly than what happened there?

Reenacting Pickett’s Charge, July 2013. (Courtesy of Alexandra Petri)

I sought answers to these questions at the battlefield visitor center and among the reenactors dragging enormous guns down winding roads to converge on a neighboring field for the 150th anniversary.

Welcome to Gettysburg

I discovered that if you want to learn what was meaningful about Gettysburg, Gettysburg may not be the place to learn it. The visitor center’s “introduction to the Battle of Gettysburg” includes surprisingly little about the battle.

That was not always the case. The Gettysburg museum and visitor center has changed its story several times over.

In 1913, for the 50th anniversary, the site installed painter Paul Philipotteaux’s massive 1884 cyclorama painting, offering a panoramic view of the battlefield on the last day of fighting. Forty feet high and the length of a football field, the cyclorama immerses visitors in the heroic Gettysburg that dominated memory for so long. Confederate soldiers, flags waving, surge to the famous copse of trees amid white clouds of cannon fire — all from the perspective of the Union troops who mowed them down.

The 100th anniversary saw the addition of an electric map. “The battle of Gettysburg was one of the most decisive battles in history,” the map boomed. “Termed the high tide of the Southern Confederacy, it is considered by many historians the turning point of the American Civil War.” A set of colored lights pursued one another aggressively across a plaster landscape, showing where the left wing of one army tangled with the right wing of the other, where the Union troop campfires flickered, and where Longstreet’s corps settled before Pickett’s Charge.

The map was removed from the visitor’s center in 2008. The new centerpiece is a film narrated by Morgan Freeman. And the battle itself doesn’t come up until more than seven minutes in, once the inevitability of a conflict between the agrarian, slave-holding South and the more industrialized North over the expansion of slavery has been made clear.

The battle is no longer framed as the turning point it once was. By the spring of 1863, Freeman informs us, the Union was winning the war on most fronts, but in the East, Confederate Gen. Robert E. Lee had been enjoying some shocking successes — Fredericksburg, Chancellorsville. “Lee believes,” the narration continues, “that another victory now, especially on northern soil, could turn the tide of the war.”

The film retains the claim that this was the ‘high-water mark’ of the Confederacy, but even with all the stirring music, you wonder if there was much of a chance. The North had vastly more railroads, manpower and natural resources than the South. How on Earth did it take them five years to finish this thing? Wasn’t the outcome a foregone conclusion?

Gettysburg reenacted

It seems less obvious when you are sweating in a field in the July heat, wearing several layers of wool, a canteen clicking at your hip as you bring ammunition rounds to the gunners.

For this exercise in memory, I am embedded in Battery M of the regular Union artillery. My face is smeared with black powder and I smell of saltpeter. I have no idea how anyone managed to do this under fire. I’m having enough difficulty when my life is in no danger.

What happened at Gettysburg? The reenactors know, and they’ll tell you, at length. Who was in this unit? Where did they fight? Why did they go here, not there? Where was the left wing marshaled?

They aren’t historians. Most of them have day jobs: In my unit, the commander runs a landscaping business, the gunnery expert is a retired veterinarian and the No. 3 man on the cannon is an assistant commonwealth’s attorney in Virginia. But they’ve absorbed all the details Everett spoke about 150 years ago, and many more. Did you see, they say, that horse-drawn caisson? Very rare. Very exciting!

One of the jokes about reenactments is that they make it seem impossible that the Confederacy could have lost the war, given that the Confederate reenactors always have the Union army outnumbered. Then again, they’re the ones who want a do-over.

In “Intruders in the Dust” (1948), William Faulkner writes about how for “every Southern boy fourteen years old, not once but whenever he wants it, there is the instant when it’s still not yet two o’clock on that July afternoon in 1863, the brigades are in position behind the rail fence, the guns are laid and ready in the woods” and it seems possible that this time “the desperate gamble” could be crowned with victory.

As a northern 20-something millennial woman, I don’t wish for an alternate ending. But standing back from the cannon’s recoil, ears covered, dimly aware of the clouds massing over the fields and the promise of rain, I can picture what a terrifying muddle it was — and how easily everything might have been different.

This randomness is the part of military history that has always fascinated me. You miss a sunken road on your map, and Waterloo is a defeat instead of a victory. You misplace three cigars with orders wrapped around them, and Antietam suddenly grows more complicated. You shoot at what you take to be an enemy riding in the woods, and you have killed Stonewall Jackson. Hold the heights for an hour longer, for two hours longer, and the course of history shifts.

Talk to any military historian about Gettysburg and you have to fight your way through a thicket of “if”s.

When we reenact the charge, one of the soliders in our unit secedes to rejoin another regiment, the North Carolinians, to run at our guns and see how far he makes it. Maybe they’ll get over the top this time. Who knows?

Is this, then, the story of Gettysburg: a historical near-miss? Is it about how close the South came, and how much was sacrificed to stop the Confederate troops?

In academic histories, one of the popular descriptions of Pickett’s Charge is as a “microcosm” of the war itself. “Matchless valor, apparent initial success, and ultimate disaster,” writes James McPherson. He quotes a union commander’s surprise: “I did not believe the enemy could be whipped.” Gettysburg broke the spell of Lee’s annus mirabilis. It was all downhill from here.

Gettysburg, more perhaps than other battles, is the sum of the stories we tell about it.

What they did here, as Everett noted and I learned in the reenactment smoke, was man their guns and fight to the death for a few feet of rocky peninsula ground.

But it was because of what Lincoln said here that the ground mattered. It was the spiritual struggle that set the site apart. Gettysburg, like the Civil War as a whole, was bloody, terrible and for a greater good.

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