John Christgau has a knack for finding riveting slivers of history hidden in complex events. He pumps fresh blood into long-forgotten characters and does it with crisp, simple writing.

A couple of years ago, his book "Birch Coulie" cut through confusing layers of the U.S.-Dakota War. His new Civil War book, "Incident at Otterville Station," does it again, capturing a dramatic, overlooked morality play involving a bunch of Ninth Minnesota Regiment soldiers stuck guarding a bridge in Missouri.

The soldiers are snapped from their boredom when a runaway slave named John runs panting into their camp, pleading for help. His master was about to ship him and 12 fellow slaves to Kentucky, where they would be sold right before slavery was abolished and the master's property became worthless.

Three dozen Minnesota soldiers, mostly farm kids from Austin and Winona, volunteered to check out his story. They get to the Otterville station minutes before the train arrives. With guns drawn, they order the train to stay put, and ignore the slave owner and a couple of Missouri militiamen who insist that they outrank these punk soldiers from Minnesota.

John and his fellow slaves disappear into the woods and the Minnesotans wind up in jail on mutiny charges when their captain throws them under the metaphorical train, saying they were acting on their own. Senators in Washington join Minnesota newspapers editors, arguing that the soldiers are heroes, doing the right thing to end slavery just as their comrades from the First Minnesota did plugging the line at Gettysburg.

Christgau, 80, grew up near Crookston and taught school in California. He describes the Minnesota ringmaster, Sgt. Francis Merchant, 21, as a French émigré from the farms near Austin, "with a handsome dark complexion and hard gray eyes that made him look older than he was. He exuded confidence, even though there were men twice his age among the volunteers. Mer-shaunt it was pronounced, giving him another distinction among the volunteers with sharp names like Felch, and Pratt and Pye."

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John Christgau

There have been other books about this chapter of the Civil War, including John Lundstrom's exhaustive "One Drop in a Sea of Blue," published two years ago by the Minnesota Historical Society Press. Christgau simply makes it more digestible.

He opens with a lavish 1863 gala in Washington honoring President Lincoln two years into the Civil War. He then drops the reader into Missouri's Pettis County, where slave owner Charles Walker awakens his six adult slaves and their seven children to inform them they are off for a train ride to the slave market in Kentucky.

The book bogs a bit as Christgau tries to explain Missouri's twisted role as both a slave state and a member of the Union. But when he gets back to the story of John and the Minnesota soldiers who freed him, readers won't be tempted to get off the train as it rolls through Otterville Station.

Staff writer Curt Brown's e-book on the U.S.-Dakota War, "In the Footsteps of Little Crow," can be found at tinyurl.com/9f73o8j