"In all wars there have always been, and always will be a class of men designated as guerillas, but it can be said that the Missouri guerillas are more noted than those of any war in any country for ages. Their deeds of daring, their miraculous escapes, and the physical sufferings that they endured are almost beyond belief." (John McCorkle, one of Quantrill's Raiders)
The Civil War is best remembered for the big battles and the legendary generals who fought on both sides, like Robert E. Lee facing off against Ulysses S. Grant in 1864. In kind, the Eastern theater has always drawn more interest and attention than the West. However, while massive armies marched around the country fighting each other, there were other small guerrilla groups that engaged in irregular warfare on the margins, and among these partisan bushwhackers, none is as infamous as William Quantrill and Quantrill's Raiders.
Quantrill's Raiders operated along the border between Missouri and Kansas, which had been the scene of partisan fighting over a decade earlier during the debate over whether Kansas and Nebraska would enter the Union as free states or slave states. In "Bloody Kansas", zealous proslavery and antislavery forces fought each other, most notably John Brown, and the region became a breeding ground for individuals like Quantrill, who shifted right back into similar fighting once the Civil War started. Rather than target military infrastructure or enemy soldiers, the bushwhackers rode in smaller numbers and targeted civilians on the other side of the conflict, making legends out of men like Bloody Bill Anderson and John Mosby.