Volume II of The Cambridge History of War covers what in Europe is commonly called ‘the Middle Ages’. It includes all of the well-known themes of European warfare, from the migrations of the Germanic peoples and the Vikings through the Reconquista, the Crusades and the age of chivalry, to the development of state-controlled gunpowder-wielding armies and the urban militias of the later middle ages; yet its scope is world-wide, ranging across Eurasia and the Americas to trace the interregional connections formed by the great Arab conquests and the expansion of Islam, the migrations of horse nomads such as the Avars and the Turks, the formation of the vast Mongol Empire, and the spread of new technologies – including gunpowder and the earliest firearms – by land and sea.