Since 1900, United States troops have fought in more foreign conflicts than any other nation on Earth. Most Americans supported those actions, believing that they would keep the scourge of war far from our homes. But the strategy seems to have failed—it certainly did not prevent terror attacks against the U.S. mainland. The savage Oklahoma City bombing in 1995 and the 11 September 2001 (9/11) attacks on New York and Washington, D.C. were not the first to inflict war damage in America’s 48 contiguous states, however—nor were they the first warlike actions to harm innocent citizens since the Civil War. Paradoxically, making war abroad has always required practicing warfare in our own back yards. Today’s large, mechanized military training exercises have degraded U.S. soils, water supplies, and wildlife habitats in the same ways that the real wars affected war-torn lands far away. The saddest fact of all is that the deadly components of some weapons in the U.S. arsenal never found use in foreign wars but have attacked U.S. citizens in their own homes and communities. The relatively egalitarian universal service of World War II left a whole generation of Americans with nostalgia and reverence for military service. Many of us, perhaps the majority, might argue that human and environmental sacrifices are the price we must be willing to pay to protect our interests and future security. A current political philosophy proposes that the United States must even start foreign wars to protect Americans and their homes. But Americans are not fully aware of all the past sacrifices—and what we don’t know can hurt us. Even decades-old impacts from military training still degrade land and contaminate air and water, particularly in the arid western states, and will continue to do so far into the future. Exploded and unexploded bombs, mines, and shells (“ordnance,” in military terms) and haphazard disposal sites still litter former training lands in western states. And large portions of the western United States remain playgrounds for war games, subject to large-scale, highly mechanized military operations for maintaining combat readiness and projecting American power abroad.