The Army of the Caesars;

From the front flap of this 366 page book: "In this dramatic and exciting book, the first general history of the army in Roman society, Michael Grant shows how the rise and decline of imperial Rome was intimately connected with the balance of political and military power. The role of the army in the Roman empire was a formidable one: the emperor depended on the soldiers for his continued existence, as the the empire itself. But an army powerful enough to defend the frontiers and keep the Roman peace also had the power to destroy the emperor. Against this ever-present danger the emperors took unceasing precautions, one of their principal methods being to surround themselves with bodyguards, the Praetorian Guard. But what began as a protective measure had wider repercussions, for the Guard came to play an even greater part in the internal politics of the empire. Thus the Roman army was a two-edged weapon: it maintained the existence of the empire, yet at the same time it very often weakened and damaged that empire by removing and setting up emperors amid savage civil strife. The history of Rome's military rulers is singularly relevant today, for there are still countries in the world where the army is in firm control of the administration. The story of 'The Army of the Caesars' provides a model of how civil strife, focused around the holders of military power inevitably occurs, endangering the precarious equilibrium of large areas of the world."