Final answer:
The Plains Wars began after the US Civil War and escalated following the Medicine Lodge Treaty, with the Battle of Palo Duro Canyon being a significant last conflict in the southern Plains. The conflict stemmed from settler encroachment and treaty failures, culminating in the Plains tribes' loss of homeland as they were confined to reservations.
Step-by-step explanation:
The Plains Wars started after the US Civil War. Following the signing of the Medicine Lodge Treaty, the fighting intensified. On the southern Plains, the last major conflict of the Plains wars was the Battle of Palo Duro Canyon in 1874 during the Red River War.
Settlers' encroachment on Native American land and the failure of the U.S. government to uphold treaty agreements led to tensions and conflict with various tribes, including the Lakota Sioux, Apache, and others. The utilization of the horse, introduced by the Spanish, had transformed the Plains tribes into highly mobile hunters and formidable warriors, exacerbating conflicts with settlers and ranchers as the westward expansion continued after the Civil War.
The Plains Wars were an era marked by battles and treaties as the U.S. government aimed to settle the "Indian problem" by confining tribes to reservations, leading to a loss of the homeland for the Plains Indians. The Medicine Lodge Treaty and others like the Second Treaty of Fort Laramie were efforts by the government to relocate Native American tribes to reservations, which ultimately furthered hostilities and led to more conflicts.