This past summer, when Comic Opera Guild managing director Tom Petiet started looking for shows to include in the group’s American Musicals in Concert series, he sought out two early 20th century pieces that had largely been lost to time. But there was one other criterion for selection.

“We wanted to do shows that …weren’t something you wouldn’t want to hear,” said Petiet. “There are a lot of those out there.”

After finding a web site that offers more than 200 MIDI files of complete operettas from this period, Petiet “auditioned” several shows until he found two that seemed fun and had good music: Victor Friml’s “Katinka” and John Phillip Sousa’s “The Charlatan.”

You might be surprised to learn that Sousa, the March King, first found success and fame as an operetta composer. But Petiet noted that this was, at the time, a common career path for up-and-coming composers.

“He played in the pit orchestra,” Petiet said of Sousa. “Back in those days, you did anything you could to make money, and of course, playing in the pit orchestra was something you could do. I think Offenbach did that, Victor Herbert did that — most of the composers were pit musicians who … started writing their own (shows).”

Sousa’s show, “The Charlatan,” which premiered in 1898, featured a book by playwright Charles Klein, and told the story of a Russian family that plots and schemes to keep a young prince from inheriting his title and estate.

Meanwhile, Victor Friml’s show, “Katinka,” opened in 1915 and focused on a young woman stuck in a loveless marriage in Russia. When her first, true love returns to her, the two embark on a quest to gain back Katinka’s freedom.

“It was a transition piece, really, because at that time period, they were morphing from what had been a European operetta tradition into a more American musical tradition, which partially was brought about by Victor Herbert,” said Petiet.

Katinka and Ivan hearken back to the European tradition, while an American couple, the Hoppers, have a more American musical comedy bent.

“You don’t really notice it all that much, though,” said Petiet. “We talk about it so you can watch for this stylistic thing that’s going on, but as far as the audience is concerned, it’s not going to be a jarring shift from one to the other. … It’s not like you’re suddenly going from Johann Strauss to Lerner and Loewe.”

In the past five years, COG has revived 35 operettas and musicals from the early 20th century — before radio and recordings made music widely available to the masses — in order to trace the roots of the American musical. In many cases, COG’s recordings are the only ones available for these shows; and because rental houses generally released show materials (to various, often-mysterious destinations) when they were no longer profitable, tracking down these shows’ dialogue can be a long, difficult process.

But even when scripts are found intact — as was the case with “Katinka” and “The Charlatan” — Petiet performs some prudent editing before COG presents them in concert form.

“We do not use the complete dialogue,” said Petiet. “These shows were often rather long. Back in those days, (patrons) had no limit on how long they wanted to stay in the theater. They wanted to be there all night. But not anymore.”

PREVIEW Rudolph Friml’s “Katinka” and John Phillip Sousa’s “The Charlatan” Who: Comic Opera Guild. What: The Guild’s “American Musicals in Concert” series continues with the presentation of these two largely-forgotten operettas. “Katinka” tells the story of a young woman in Russia who’s trapped in a loveless marriage until her first love returns; and “Charlatan” focuses on a Russian family that schemes to keep Prince Boris from inheriting his title and estate. Where: Vitosha Guest Haus Inn, 1917 Washtenaw Ave. When: “Katinka” on Thursday, November 5 and Saturday, November 7 at 8 p.m.; “Charlatan” on Friday, November 6 at 8 p.m. and Sunday, November 8 at 2 p.m. How much: $15 ($12 for seniors, and on Thursday, all tickets cost $10). Info: For tickets, call 734-763-8587 or visit Ticketmaster online or in person.

Jenn McKee is the entertainment digital journalist for AnnArbor.com. Reach her at jennmckee@annarbor.com or 734-623-2546, and follow her on Twitter @jennmckee.