This lecture will explore the ecological and environmental effects of military activity—whether engaged in or preparing for combat—over the 20th century. We will pay particular attention to major wars involving the U.S.: WWI, WWII, Korea, Vietnam, and the First Gulf War, with additional consideration of the global environmental impacts of the Cold War. While destruction of nature is a certain result in any war, nature is also resilient and can rebound from conflict in hopeful and beneficial ways.