Few recordings can claim as much gravitas, or as much ambition, as Songs of Slavery & Emancipation. It consists of two CDs, each devoted to one of the mentioned states of being, linked by their commitment both to past historical authenticity and to continuing political resistance. The songs, tunes and (in one instance) poem also have in common their obscurity in our century, meaning that they're the products of deep research. There are standard slavery songs -- "O Freedom," "Follow the Drinking Gourd," "No More Auction Block for Me" and "Let My People Go" come to mind -- but you won't find them here.

The project began in 2015 when activist/writer/musician Mat Callahan came upon a 1930s monograph by Herbert Apthecker, the then-prominent historian associated with the Communist Party USA. His political affiliation drove an interest in persecuted individuals and groups, common enough in American historical scholarship of recent decades but then unusual when a consensus reading of the national story prevailed and slaves and rebels remained on the scholarly margins.

Apthecker uncovered a song, "Hymn of Freedom," from 1813. Sung to the tune of "Hail Columbia," it outlined a plan for slave rebellion, the sort of thing for which anyone who sang it could have been killed. (More than a century later, Southern blues musicians rarely as much as hinted at their oppressed circumstances for the same reason.) The discovery led Callahan to dig for comparable material and to bring historians and musicologists who shared his interest into the search. This year the harvest has been this album (released as a mini-book with extensive notes), a full-length volume published by the University of Mississippi Press, and a documentary film. I haven't read or seen the latter two at this moment, though I hope to do so soon.

Meantime, the music on Disc 1 opens joltingly with "Agonizing Cruel Slavery Days," looking backward not long after the end of the Civil War. "Hymn of Freedom" is among the songs that follow, performed in a range of period styles, from formal choral arrangements to folk songs and spirituals that would have filled the air in more casual circumstances. Practically none of this will be known to any but a tiny handful of listeners. Though I am no authority on the subject, I am reasonably versed in 19th-century popular and traditional music, and I have heard a fair number of slave songs as done by gospel groups and traditional singers. Still, the sole cut on either disc that I recognize is Henry Clay Work's "Kingdom Coming" (1862).

A successful composer of popular songs (he would also write "Babylon is Fallen" and "Grandfather's Clock," still known and revived on occasion), the Chicago-based Work was sympathetic to the abolitionist movement. His father had been active in the Underground Railroad. In an America in which white racism was entrenched and impossible to escape, abolitionists were disdained, sometimes violently so, even in the North; thus, many -- albeit, in fairness, not all -- who fought for the Union insisted that their objection was solely to secession, not to ownership of human beings of a darker skin color. A good share of the nation's white population knew no Black people personally but had their perceptions shaped by the "darkies" -- blacked-up Caucasians -- who toured in minstrel shows pretending to be African-Americans of happy, simple-minded disposition and funny speech.

Except for its storyline, an irony-laden parable of a world turned upside down when a terrified "massa" flees as Union gunboats appear just up the river from the plantation, "Kingdom Coming" could be a tune from the minstrel stage. Told from the slaves' perspective, the song carries barely a word of conventional English. The first two lines:

Say Darkeys, hab you seen de massa, wid de muffstash on his face,
Go long de road some time dis mornin' like he gwine to leab de place?

This would be astonishingly offensive if taken out of context. Yet it belongs on this album, where it is done as a banjo tune with the minstrel language intact. The song concerns the slaves' unbridled joy at their liberation, showcased not only in the lyrics but in the song's irresistibly jaunty melody. The slaveowner is craven and cowardly, just as slaves were represented in minstrel shows and popular culture generally. Work knew his audience, overwhelmingly working-class white and decidedly out of sympathy with the struggle for Black freedom. As Christian McWhirter observes in Battle Hymns: The Power & Popularity of Music in the Civil War (University of North Carolina Press, 2012), "Work understood that he did not need to overcome his audience's racial prejudices to generate support for emancipation. It was precisely by using the racial stereotypes of minstrelsy that he was able to achieve such a high degree of success."

As one would expect, the other songs, from Black composers and their white allies in the abolition movement, employ a more straightforward strategy to engage participants and listeners. Some are deadly serious; others demonstrate varying kinds of humor, sometimes bitter, never more so than in "Song of the 'Aliened American'," a parody of "My Country 'tis of Thee" from 1854:

My country 'tis of thee,
Dark land of slavery.

"The Negro's Complaint," from the early 19th century, borrows the melody associated with the hymn "Old Hundred" (or, as I knew it in my junior Lutheran days, "The Doxology"). I won't try to estimate how many songs from that period found themselves fixed to the "Rosin the Beau" tune. Though I thought I'd heard them all at one point or another, "The True Spirit" is fresh to my attention. A particular delight, "Flight of the Bondman" deserves to be far better known and to be swept into the American folksong canon. From my decades-stretching interest in the Civil War era, I am conscious of the campaign to allow Black men into Union uniforms; yet I learn only here of "The Enlisted Soldiers," sometimes called "The Negro Battle Hymn," celebrating the effort's success against the hostility of powerful bigots. It may be the single most stirring cut on the album.

I suppose you could call these "protest songs," and they are that. Like all the others that answer to the designation, they are sermons set to music. But they're also songs, and they're all good ones, and some are more than that. Which is to say that Songs of Slavery & Emancipation is eminently listenable, a gift to soul and spirit.

None of the various artists are identified anywhere in close proximity to a recorded performance. You have to go to the back of the book to find out, in a general way of speaking, whose voices you're hearing. You learn that the album was cut in six locations, most not close to each other, one as far-flung as Bern, Switzerland. Besides Callahan's, I recognized two names, both from the folk scene: Tim Eriksen and Eli Smith. I couldn't tell you, though, where they appear. Not that it matters. Nobody's grandstanding, and everybody is a hopeful but modest passenger aboard the freedom train.

Finally, a gentle suggestion: This had to be incredibly expensive to assemble. You can do your part by putting something back in. Buy a copy today. It will prove you're a good person, and its dark subject notwithstanding, it will introduce you to some of the most remarkable songs ever sung in America. Songs of Slavery & Emancipation is nothing less than a triumph.