In Missouri, military action was not typically defined by large, formal armies meeting on clearly defined battlefields. Instead, small bands of guerrillas and soldiers skirmished in the backcountry and wilderness. Guerrilla activity pervaded all areas of the state, and the Union army struggled throughout the war to control it. The general population was often caught in the middle, subjected to the unconventional methods of guerrilla warfare employed by both sides that resulted in a brutal and psychological conflict. At the same time some of the populace exacerbated the problem by supporting the guerrillas, often providing them with food, clothing, arms, and horses.

Guerrilla activity devastated homes, families, and entire communities for the duration of the war and even afterward. Bands of fighters appeared from nowhere and faded back into farmlands as abruptly as they had come. Unchecked guerrilla warfare was a threat to everyone in the state: Rebel guerrillas harassed the Union army, Union guerrillas harassed the rebel army, civilian guerrillas terrorized civilians with sympathies to both sides, and outlaws with ties to no side harassed everyone indiscriminately.