When the Civil War broke out in April 1861, Kansas was in a unique position. Although it had been a state for mere weeks, its residents were already intimately acquainted with civil strife. Since its organization as a territory in 1854, Kansas had been the focus of a national debate over the place of slavery in the Republic. By 1856, the ideological conflict developed into actual violence, earning the territory the sobriquet "Bleeding Kansas." Because of this recent territorial strife, the state's transition from peace to war was not as abrupt as that of other states.

Kansas's War illuminates the new state's main preoccupations: the internal struggle for control of policy and patronage; border security; and issues of race—especially efforts to come to terms with the burgeoning African American population and American Indians' continuing claims to nearly one-fifth of the state's land. These documents demonstrate how politicians, soldiers, and ordinary Kansans understood the conflict and were transformed by the war.