The historian Polybius (ca. 200--118 BCE) was born into a leading family of Megalopolis in the Peloponnese and served the Achaean League in arms and diplomacy for many years, favoring alliance with Rome. From 168 to 151 he was held hostage in Rome, where he became a friend of Lucius Aemilius Paulus and his two sons, especially Scipio Aemilianus, whose campaigns, including the destruction of Carthage, he later attended. Late in his life, as a trusted mediator between Greece and the Romans, he helped in the discussions that preceded the final war with Carthage, and after 146 was entrusted by the Romans with the details of administration in Greece. Polybius' overall theme is how and why the Romans spread their power as they did. The main part of his history covers the years 264--146 BCE, describing the rise of Rome, her destruction of Carthage, and her eventual domination of the Greek world. It is a vital achievement of the first importance despite the incomplete state in which all but the first five of its original forty books have reached us. For this edition, W. R. Paton's excellent translation, first published in 1922, has been thoroughly revised, the Buttner-Wobst Greek text corrected, and explanatory notes and a new introduction added, all reflecting the latest scholarship.