As Brazil, Russia, India, China, and Europe rise in global influence, twenty leading historians from four continents take a timely look backward and forward to discover patterns of eclipse in past empires that are already shaping a decline in US global power, including the erosion of economic and fiscal strength needed for military power on a global scale; misuse of military power through micro-military misadventures; the breakdown of alliances among major powers; and insufficient technological innovation to sustain global force projection.