As recently as the 1980s, archeologists focusing on prehistoric eastern North America paid little attention to intergroup conflict.[1-3] Today the situation is quite different, as indicated by this Special Issue. Archeologists now face three principal challenges: to document the temporal and spatial distribution of evidence of conflict; to identify the cultural and environmental conditions associated with variation in the nature and frequency of warfare over long periods of time and large geographical areas; and to determine the extent to which intergroup tensions contributed to or resulted from changes in sociopolitical complexity, economic systems, and population size and distribution. We present data from habitation and mortuary sites in the Eastern Woodlands, notably the midcontinent, that touch on all three issues. Palisaded sites and victims of attacks indicate the intensity of conflicts varied over time and space. Centuries-long intervals of either high or low intergroup tensions can be attributed to an intensification or relaxation of pressure on resources that arose in several ways, such as changes in local population density; technological innovations, including subsistence practices; and the natural environment.