An impeachment means history, and history means attention, and attention means money. Big events sell a lot of papers, as they used to say, though of course, they don’t sell as many newspapers as they used to. Instead, major news events sell just about anything else, from “Impeach 45” buttons on CafePress to impeach-mints on Zazzle. Anytime something that a lot of people care about rises to the country’s attention, someone is there to sell them a related product.

While the availability of universal tools for such entrepreneurship is new, the sentiment isn’t. Consider America’s first impeachment, that of Andrew Johnson. While that 1868 event certainly sold a lot of newspapers, entrepreneurs also found other ways to make money on an event that had captured the nation’s attention.

Including with a polka.

That’s “Impeachment Polka,” written in 1868 by the composer Charles Dupee Blake. It’s an odd artifact of the moment but only in the abstract — only in the way that a mass-produced button depicting a peach with a blond coif might be to an observer 150 years from today. By all accounts, Blake’s polka aimed at precisely the same goal: turn something everybody was talking about into a little pocket change.

And make no mistake. In 1868, everybody was talking about the Johnson impeachment.

“Tickets to the impeachment trial in the Senate for Johnson in 1868 were the hottest items in town,” said Brenda Wineapple, author of “The Impeachers: The Trial of Andrew Johnson and the Dream of a Just Nation,” when we spoke with her by phone Wednesday. “They were very hard to get hold of. People were lined up outside the building early in the morning to try to get in.”

Newspapers printed multiple editions a day in some places with updates on the developments — and on the drama surrounding it.

“The newspapers were not only covering what was going on, but they were covering who was there, who was sitting in the ladies gallery, what were they were wearing,” Wineapple said. “It was very built into the culture — and it was a major cultural event.”

And, she said, a lot of people were capitalizing on it.

Including composer Charles D. Blake. That might seem like an odd occupation from which to try to make a buck off politics, but remember, this was only three years after the end of the Civil War. The phonograph wouldn’t be invented for almost another decade. It was a time when many middle- and upper-class homes had pianos and, in lieu of recordings of favorite songs, families would buy sheet music that allowed them to play the songs themselves.

Sheet music “was really a big business,” said music bibliographer Donald W. Krummel in a phone conversation with The Washington Post. “It was all over the country, little publishing firms in little towns but also in big cities.”

“This is like rock today,” he added. “It was a popular business.”

The biggest publisher of them all, he said? Oliver Ditson in Boston — the publisher who produced “Impeachment Polka.”

It’s not clear how this particular piece came about. Krummel speculates that perhaps Blake, a prolific composer, approached Ditson with the idea.

“He was a, kind of a hack composer who ran a music shop and did the composing on the side, or maybe had assistants who did the work for him,” Krummel said. “But he was involved in ‘producing’ music, which he himself may have published or he may have sent to other big publishers. In this case, I think Ditson said, ‘hey, this is interesting; this is very timely. We’ll give you fifty dollars for it’ ” — a guess at the sort of relationship that may have been at play. (The music sold for 30 cents a copy.)

That dynamic is speculation on Krummel’s part. He noted that it was also possible that Ditson contacted Blake with the idea of putting together something pegged to the impeachment. The point being that the likely motivation was profits, not politics.

Blake, who composed hundreds of these “salon trifles” over his career, according to the Petrucci Music Library, would seem like a natural composer to commission. When he died in 1903, he earned a mention in the New York Times, which described him in a brief item as a “well-known composer” — whose best-known work was “Rock-a-bye Baby.” (This is disputed.)

The choice of a polka was itself likely an effort to broaden the market appeal of the song.

“In 1868 … the polka and the waltz and the mazurka and the gallop were the most popular ballroom dances, other than a quadrille, which is like a square dance,” said Carol Téten, an expert on historical dance. The polka, in particular, was embraced, regardless of age or economic status.

“It is probably one of the most far-reaching couple dances, even more so than the waltz, because it’s easier to do than the waltz,” she said. “It’s boisterous and happy and explosive and freeing. From kids all the way through, you can do it.”

If you wanted to sell as many copies of a piece of sheet music as possible at that moment, Téten said, the polka was a good choice.

The piece itself appears to have avoided one possible constraint on its appeal. With no lyrics — it was likely written to be danced to, Krummel said — it didn’t seem to advocate any particular position on the impeachment itself.

Johnson had become president three years prior, shortly before the end of the war. He had served as Abraham Lincoln’s vice president, a Democrat serving a Republican. When Lincoln was assassinated, Johnson took over and, in short order, found himself in a contentious relationship with the Republican majority in the Capitol. (Many states that had been part of the Confederacy — and which were mostly Democratic — had not yet met the conditions that allowed them voting roles in the House and Senate.)

The impeachment itself stemmed from Johnson’s violation of a law passed by Congress, which sought to limit his ability to fire members of his administration, Wineapple said. When Johnson then moved to fire Secretary of War Edwin Stanton, the House moved quickly on a vote to impeach. The vote broke down largely along party lines with a few members of the majority joining the minority in opposition.

(Among the Democrats voting against impeachment in the first vote that February? Ohio's Philadelph Van Trump.)

The House delegation from in and around Boston, home of both Blake and the publisher Ditson, voted to impeach. Again, though, that probably wasn't the impetus for the resulting composition.

“We have to be careful, then, as now, in assuming, say, that the Northeast was all for something and the South was all against it,” Wineapple said. “What’s also interesting and different from today is that most everyone didn’t like Johnson, in terms of political parties. But whether they wanted the impeachment to remove him from office was a completely different story.”

Johnson’s Senate trial began in early March 1868 and lasted into May. It’s not clear when “Impeachment Polka” was first released, but an advertisement in the Portland (Maine) Daily Press, from April 30 of that year shows how it had already moved out to music stores — including Portland’s, appropriately enough on Congress Street — as the trial was underway.

Notice that Blake is identified by name, suggesting an existing familiarity with his work.

Michael Adcock, a pianist from the Washington Conservatory of Music who performed the piece for The Post, noted a possible subtext to the polka itself.

“It’s sort of satire,” he said. “There’s a little tongue-in-cheek element about the piece. He has an introduction which portends something serious or is going to transpire — but by the time we finish the end of the introduction it all of a sudden it turns into a polka. There’s an exuberant festivity, I think, about the piece that’s very charming, but it’s a piece of an era.”

While that is clearly true, the sentiment underscoring its creation and the moment in which it came to be are universal.

The impeachment “was very much part of what was going on at the time in a certain sense, like today,” Wineapple said. “Although, I think, also like today, there are people who aren’t paying any attention at all. That’s probably going to always be the case.”

An unfortunate and eternal upper limit to potential sales in any era.