With the end of the Civil War, the U.S. resumed its westward expansion and absorption of Indian tribal lands, setting off a conflict that would last more than three decades.

Historian Peter Cozzens offers an evenhanded look at that bloody struggle between whites and Native Americans, drawing from his new book The Earth Is Weeping: The Epic Story of the Indian Wars for the American West.

Cozzens, recently retired as special assistant to the historian of the U.S. State Department, touches on tribal disagreement over whether to fight or make peace, the squalid lives of soldiers posted to the frontier, and the ethical quandaries faced by generals who often sympathized with their native enemies.