From the years 58 to 50 BCE a campaign of conquest in the region north of the Alps known to the Romans as Gaul was led by the ambitious Roman statesman Gaius Julius Caesar (Figure 11.1). The cost in human lives of this campaign was prodigious, with the biographer Plutarch recording in the first century CE that 1 million people were killed and 1 million enslaved – miraculously balanced numbers.1 Such extraordinary figures have unsurprisingly attracted attention in discussions of the application of the concept of 'genocide' to the ancient world. Indeed, Raphael Lemkin, the Polish jurist who coined the term 'genocide', had himself intended to write a chapter on 'Genocide in Gaul' in his own unfinished History of World Genocide.2 While some have been willing to use the label 'genocide' for Caesar's actions,3 the matter remains controversial, both in terms of the specific case of Caesar, and the general question of whether 'genocide' is an appropriate concept to apply to the premodern era.4 As Nico Roymans summarises, 'the concept (of genocide) has a specific, highly negative meaning in our modern society, which is why some scholars have argued that it is anachronistic when applied to mass killings in premodern periods'.5 Although, as we shall see, ancient mass violence did not occur in a moral vacuum, nonetheless it is clear that the intentional destruction of a people could, in certain circumstances, be regarded as not only morally acceptable but even praiseworthy.