This publication offers a lucid and well-researched analysis of irregular warfare during the American Civil War. Dr. Martin's focus on insurgent operations in the western border region brings fresh insights to this area of study. Moreover, the history of insurgency in these western states offers a greater understanding of irregular warfare to those who may be tasked with mounting counterinsurgency operations in the not so distant future. This short period in American History has captured the imagination of Americans and spurred them to consume the many volumes written about this brother-against-brother conflict. Most of these volumes have dealt with the important battles of the war, which pitted massive armies from the North and South against each other in a struggle to determine whether the country would separate or stay together. These battles, highlighted by Gettysburg, Antietam, Vicksburg, Fredericksburg, and others too numerous to mention, were the predecessors of similar grand conflicts that would rack Europe and the world in the decades to follow. For the first time in history, an entire nation mobilized to conduct a war that would eventually spill over and affect most of the population. From the gentlemanly preparation for the First Battle of Bull Run to the consuming power of Sherman's march to the sea, the American Civil War involved far more of the American population than war in Europe historically had involved. Least understood of the effects on this population, and least studied, is the personal war conducted in the Border States, where the North met the South. This violence was not the type found on the battlefield at Gettysburg, where hoards of men in blue or gray shot at each other from considerable distance, finally moving to close quarters combat. This was a war pitted men with strong beliefs supporting one side against individuals they believed to be their enemy. The hatreds and feuds that stayed below the surface in a civilized society were freed by the all-consuming violence of this war, allowing men to act in ways that would have been unacceptable at any other time. While the Union officials tried to establish rules of war to control this personal violence, they were markedly unsuccessful. The border war would eventually degrade to such a level that death was not enough punishment for supporting the wrong side. Actions previously reserved to savages and uncivilized people would now become common as a part of the border violence. This breakdown in society may be a major reason this part of the war has been given inadequate attention over the years. Through the Second World War, combat was for the most part still a relatively conventional event, with the rules being followed by the belligerents under a common agreement. Since then, more and more conflicts throughout the world have been fought unconventionally. The more common occurrence of this type of conflict has given it more credibility as a viable form of warfare and has sparked a growth in the study of irregular warfare through history. While the reality is that larger military nations continue to question the validity of this type of warfare, it has become commonplace in the modern world and has to be understood. This study is a product of that movement to further understand irregular warfare and examine its importance in history. The author hopes to clarify this portion of the greater conflict, portraying the social and psychological impacts on the population of the border, as well as the military effects generated by the irregular war and attempts to show the parallels that exist between actions and reactions during this conflict and similar instances in the more modern irregular war fought in Iraq and Afghanistan. This is not meant to be a history of these more modern conflicts, but to point out the similarities that exist in the actions of regular and irregular warriors in these two periods.