America's Global Role, a collection of essays and reviews on national security, geopolitics and war, combines a broad historical and geopolitical overview of U.S. national security policy with commentary on historical events and biographical sketches of historical figures. This book offers insights into the evolution of U.S. national security policy from the founding to the present. Sempa shows how the United States began as a sliver of territory on the eastern seaboard of central North America; pursued a policy of westward expansion by diplomacy, war, and conquest, exploiting the European balance of power; formulated and implemented national security doctrines designed to protect its security and promote further expansion; and survived a terrible Civil War that threatened to halt that expansion. Afterwards, America began to play a larger role on the global stage. During the first half of the twentieth century, the U.S. acted as an "offshore balancer" to restore the balance of power on the Eurasian landmass. Later, the U.S. became the geopolitical successor to the British Empire. The end of the Cold War produced an initial period of uncertainty in U.S. national security policy that ended with the events of September 11, 2001, as U.S. national security policy focused on efforts to defeat global Islamic terrorists and rogue states seeking to acquire weapons of mass destruction. Sempa points out the political, demographic, and geopolitical developments of the early twenty-first century that have shifted the focus of U.S. national security policy from Europe to Asia.