What did the Gauls ever do to Rome?

This book is a timely contribution to a number of fields that dominate the ancient historical agenda, including the way that the Romans perceived their world, the differences from and similarities with Greek agendas, and the impact of Rome on its empire. It is a sign of the elegance and value of the book that it will long continue to be an important contribution to our knowledge. This is above all a much-needed treatment of a region of Italy that produced such quintessentially Roman writers as Catullus, Livy and Virgil, yet was inextricably bound up with Rome's most feared foe, the Gauls.

The book begins with the question of why Caesar chose to attack Gaul in 59BC; how had Gaul become the stigmatised acceptable enemy of the Roman regime? This question provides what is one of the most important dynamics of the book, and one that lifts it from being another demonstration of the construction of the "other" in ancient literature. J.

H. C. Williams wants to understand how the perceptions of the Gauls affected historical actions.

The first two chapters focus on Polybius and Cato the Elder, our two major sources from the middle-Republican period. Polybius sees Gaul in the context of Hellenistic geography more generally. Roman interventions in northern Italy are part of the expansion of Rome's empire, a subject that required explanation. For Cato the Elder, the wider themes are less visible, but the detailed knowledge is greater and stems from the practical Roman representation of empire in maps and itineraries, and from Cato's knowledge of the area. Cato's Gauls are newcomers and invaders; they lack the depth of historical association that the Romans felt they had acquired from their engagement with the East. For Polybius, the character faults of the Gauls are similar to the flaws that left the Greeks vulnerable, such as giving way to illogical passion, lack of foresight and a susceptibility to panic and fear.

Williams shows how writing about other people was a way of writing about oneself. Whether Cato and Polybius were representative of Greek and Roman culture seems less clear. Cato, the immigrant Sabine, and Polybius, the Greek friend of Scipio, may have been more personal in their outlooks.

Detailed consideration of the conflicting narratives of the invasion of Italy and sack of Rome in the 4th century demonstrate the ways that preconceptions drove the narrative shape. Livy, himself from Padua, gave the Gauls a venerable presence in northern Italy. Williams makes a strong case, here and in the last chapter, for the contextualisation of much of this in the debate over the enfranchisement of Transpadane Gauls, connected with Caesar's definition of the Alps as the border of Gallia and therefore the southern limit of his province. It was the sack of Rome, though, that lived in people's minds, and Rome's fearful memory gave legitimacy to its actions. The fate of Rome always seemed bound up with its northern neighbours - ironically, of course, in the long term it was.

The book begins and ends with issues of identity, "Celticity", and Williams approaches these through the distinction between external categorisation and internal sense of community. The modern development of independence movements in northern Italy is juxtaposed with the complex identity of its ancient inhabitants. The powerful demonstration that the ways one thinks about one's enemy dictate one's actions is no less resonant.

Christopher Smith is professor of ancient history, University of St Andrews.