Book excerpt: Volume IV of The Cambridge History of War offers a definitive new account of war in the most destructive period in human history. Opening with the massive conflicts that erupted in the mid nineteenth century in the US, Asia and Europe, leading historians trace the global evolution of warfare through 'the age of mass', 'the age of machine' and 'the age of management'. They explore how industrialization and nationalism fostered vast armies whilst the emergence of mobile warfare and improved communications systems made possible the 'total warfare' of the two World Wars. With military conflict regionalized after 1945 they show how guerrilla and asymmetrical warfare highlighted the limits of the machine and mass as well as the importance of the media in winning 'hearts and minds'. This is a comprehensive guide to every facet of modern war from strategy and operations to its social, cultural, technological and political contexts and legacies.