Disunion follows the Civil War as it unfolded.

On July 18, 1861, the 12th Massachusetts Volunteer Infantry left Fort Warren, in Boston Harbor, and marched through the city for an official review on the Boston Common. Leading the way was the regiment’s colonel, Fletcher Webster, the eldest son of Daniel Webster. The regiment’s association with such an eminent personage endeared it to Boston’s most respectable citizens, who lined the streets and cheered as the men trooped by. On the Common, Edward Everett, representing the “ladies of Boston,” presented the regiment with an ornate flag — and then with an equally ornate celebratory address.

But the day’s high point occurred after the festivities, when the men marched back to the fort and the entire regiment took up the song for which they would soon become famous. “John Brown’s body lies a mouldering in the grave/ His soul’s marching on!” they sang, and then belted out the chorus: “Glory, Hally, Hallelujah/ His soul’s marching on!”

Rare Book Manuscript and Special Collections, Duke University

The song, adapted from a Methodist camp meeting hymn, had emerged from the improvisations of earlier volunteer militiamen at Fort Warren, the Second Battalion, Light Infantry. When the 12th moved in, they inherited the song and embraced it as their own. “John Brown’s Body” quickly made its way outside the fort’s walls. A month after the ceremony on the Common, a Boston publisher released sheet music for a version of the song, announcing, “[a]t this time one can hardly walk on the streets for five minutes without hearing it whistled or hummed.”

After the 12th introduced the song to the residents of New York as it marched down Broadway, the New York Tribune, one of the nation’s largest circulating papers, republished the lyrics. The song’s popularity continued to mount as the 12th made its way to the front, intermingling with other regiments. It soon spread to the entire Army of the Potomac, becoming the Union’s most beloved anthem. With its steady, determined cadence, “John Brown’s Body” seemed to steel men for battle. “The leaders of the Union army acknowledge its superhuman power for inspiring the ranks,” wrote one journalist. But what did Union soldiers mean by singing it?

The song clearly conjured up the memory of John Brown, the radical abolitionist who in October 1859 led a small band of men on a doomed raid on the federal armory in Harper’s Ferry, Va. Brown was captured and hung after spending six weeks in jail, impressing even his captors with his stoicism and Puritanical resolve. At memorial services across the North, pulpits rang out with declarations that John Brown would live on.

To some extent, the Civil War’s most popular song guaranteed this fate. For a dedicated core of abolitionists, and for those enlistees in the Union army who were impelled by antislavery ardor, “John Brown’s Body” served as a rallying cry. “I want to sing ‘John Brown’ in the streets of Charleston,” announced one Massachusetts infantry captain to his mother, “and ram red-hot abolition down their unwilling throats at the point of the bayonet.” As the song spread through the Union ranks, these abolitionists regarded its popularity as portending the incorporation of Brown’s antislavery zeal into the North’s war effort, which would ultimately culminate in the emancipation of the slaves.

Perhaps no group appreciated the song’s emancipationist associations more clearly than African Americans. “John Brown’s Body” assumed a prominent place in both spontaneous and planned celebrations of emancipation. Indeed, for bondsmen and women who intuited that freedom was no longer a distant, millennial vision, but an imminent actuality, the song clearly held a subversive attraction: when a visitor to Virginia expressed surprise in hearing slaves singing “John Brown’s Body” while laboring in the fields, he asked their master why he allowed them to do so. He was powerless to stop them, the master replied.

But when Northerners belted out “John Brown’s Body,” were they really celebrating Brown’s racial egalitarianism, and pledging the Union’s might on its behalf? To invoke John Brown in song could mean different things to different people. In fact, when the Massachusetts Second Battalion first improvised the verse about Brown marching on, they were inspired by a member of their own battalion, a Scotsman who shared the famous abolitionist’s name. (In the decades after the war, when the Scottish John Brown’s role in the song’s origins came to light, some claimed that it disproved the song’s antislavery associations. This was, of course, ridiculous, since most of the soldiers and civilians singing the song were not privy to the battalion’s joke.)

Moreover, the song’s popularity did not necessarily register the prevalence of widespread abolitionist sentiment, let alone Brown’s radical racial egalitarianism. The song, after all, makes no explicit mention of slavery or freedom, nor does it state precisely what purpose Brown’s soul would serve in marching on after his body mouldered in the grave. The song instructed soldiers and civilians in the necessity and glory of sacrifice, but it was a sacrifice that could be abstracted from any particular political, economic or social reform program.

Furthermore, when soldiers sang the song, they gave special emphasis not to the first verse, proclaiming the eternal vitality of John Brown’s soul, but another, which promised to “Hang Jeff Davis to a sour apple tree.” For many, the violence that the song celebrated had little connection to Brown’s holy purpose; to the extent that John Brown’s soul marched on with these troops, it was re-animated not by the persistence of his antislavery principles so much as by his unembarrassed embrace of violence as a means of achieving them.

And so “John Brown’s Body” could serve as an especially potent instrument of anti-Confederate animus and aggression, a sort of musical thumbing of the nose that did not necessarily specify any ideological foundation for the gesture. When a number of the men from the 16th Connecticut regiment were captured by a detail of North Carolinians, “they howled into the ears” of their Confederate captors “John Brown’s Body.” Hearing the fierce singing, “one would have supposed that we were the captors and they the prisoners,” a veteran recalled. And when the 4th Michigan Cavalry, the regiment that captured Confederate president Jefferson Davis, marched to Macon with their prized prisoner, the regimental band played “John Brown’s Body.”

Related Disunion Highlights Explore multimedia from the series and navigate through past posts, as well as photos and articles from the Times archive. See the Highlights »

Not surprisingly, Union troops often chose to mark their triumphant conquest of Confederate cities by singing the song. It became a sort of anthem for Gen. William Tecumseh Sherman’s March to the Sea, the scorched-earth campaign he led from Atlanta to Savannah, Ga. After his troops burnt down much of Atlanta and prepared to leave the city, the regimental band of the 33rd Massachusetts began playing “John Brown’s Body.” Upon leaving the smoldering city, Sherman commented, “Never before or since have I heard the chorus of ‘Glory Glory Hallelujah’ done with more spirit or in better harmony of time and place.”

So did the song celebrate the enduring incorporality of war’s aims or the vivid corporality of war’s effects? Did its message adhere more to John Brown’s triumphant soul or to Jeff Davis’ swinging corpse? It was largely the incongruities of its extemporized verses that led several antislavery writers, most famously Julia Ward Howe with her “Battle Hymn of the Republic,” to appropriate the song’s tune but to rewrite the lyrics, granting them an unambiguously abolitionist meaning. Yet, in the final months of the war, when much of the North seemed to interpret victory as a providential blessing stemming from the emancipation of the slaves, there seemed to be little ambiguity clinging to the abolitionist associations of “John Brown’s Body.” When, for instance, black troops sang “John Brown’s body lies mouldering in the grave” while marching through the streets of Charleston, S.C., William Lloyd Garrison, for decades the North’s leading abolitionist, broke down and wept, exclaiming, “Only listen to that in Charleston streets!”

Then again, just as the song could support many different interpretations, so could the war itself. When, in the decades after the conflict’s end, the North and South embraced a culture of sectional reunion in which the war was remembered less as a struggle over slavery than as a tragic, ideologically neutered contest pitting the brave boys in blue and grey, “John Brown’s Body,” with its fiercely partisan and sectional understanding of the war, became increasingly viewed as an inconvenient, and even distasteful, irritant. When the Fisk Jubilee singers, one of the nation’s most prominent African-American singing groups, performed “John Brown’s Body” in Britain during several tours in the 1870s, it met with rapturous applause. But in the United States, one of the singers recalled, the song was “almost received with groans.” The group eventually left it off many of their program. The song continued to be sung by those who wished to protest the reconciliation between North and South, premised on denying the emancipationist meaning of the Civil War. But in most postbellum ceremonies, “John Brown’s Body” was displaced by one of its musical offspring, the “Battle Hymn of the Republic.”

With its powerful biblical imagery, the “Battle Hymn” could communicate much of the millennial enthusiasm that had animated John Brown and his supporters. But the hymn could not match the anarchic, democratic vitality that Brown had also bequeathed to the song that bore his name. The loss was significant. For as the 19th century closed and the nation’s racial animosities hardened, Americans who struggled to achieve justice for both whites and blacks surely appreciated that it would take more than a song, no matter how powerful or popular, to ensure that John Brown’s soul marched on.

Follow Disunion at twitter.com/NYTcivilwar or join us on Facebook.

Benjamin Soskis, left, who recently completed his doctorate in history at Columbia, and John Stauffer, chair of the History of American Civilization program at Harvard, are writing a book about the “Battle Hymn of the Republic