Prior to the arrival of English American settlers on the Great Plains, the Southern Plains tribes had evolved into a nomadic pattern of existence. Beginning in the 1830s significant numbers of permanent settlements were established in what had previously been the exclusive territory of the Indigenous peoples of the Americas. Attacks, raids, and counter-raids occurred frequently. Prior to the Civil War, the U.S. Army was only sporadically involved in these frontier conflicts, manning forts but limited to a handful of larger expeditions due to manpower limitations. During the Civil War, the Regular Army withdrew almost completely and Indian raids increased dramatically. Texas, as part of the Confederate States of America, lacked the military resources to fight both the Union and the tribes.