What makes a battle decisive? Jonathon Riley draws on his personal experience as a soldier and historian to explore the definitive battles of the modern era from Yorktown in 1781 to Operation Desert Storm in 1991. Each battle included is a turning point, the outcome of which has changed the face of history. The battles at Ligny, Quatre Bras and Waterloo in 1815 concluded more than twenty years of war with Revolutionary and Napoleonic France and instituted alliances that dominated Europe until 1860. The Ardennes in 1944 was decisive because Hitler threw away the last army he had which could have stalled the Allied advance into Germany. The war ended less than five months later. Dien Bien Phu confirmed the collapse of French colonial power in Indo-China, and paved the way for US involvement in Vietnam to stem the tide of Communist expansion. Since Operation Desert Storm no battle can be said to have been decisively concluded and the closing chapter looks to 21st century emergencies where opponents abandon conventional conflict.