From the 1840s onward, United States military forces clashed with the Apache, a group of Native American peoples associated with the southwestern part of North America. US territorial expansion and conflict - first with Mexico and then during the Civil War - led to an escalation of hostilities that culminated in the defeat of the Apache leader Geronimo in 1886, although fighting continued into the 20th century. In this study the clashes at Cieneguilla (1854), First Adobe Walls (1864), and Cibecue Creek (1881) are assessed in detail.