Here’s Karissa Marken of the American Civil War Museum giving a presentation on guerrilla warfare in the Civil War and how guerrillas became desperadoes after the Civil War.
The video’s description reads, “American Civil War Museum intepretation specialist Karissa Marken talked about Civil War guerilla fighters who later became outlaws in the West including Jesse James, his brother Frank, and their gang. This event was recorded by the American Civil War Museum in June 2016.”
Some of the information she gives in an offhand manner is wrong, such as saying John Brown killed people because they disagreed with him. That’s a huge oversimplification, so much that it’s actually wrong.