John D Grainger analyses the Roman imperial succession, demonstrating that the empire organized by Augustus was fundamentally flawed in the method it used to find emperors. Augustus’ system was a mixture of heredity, senatorial and military influences, and these were generally antagonistic. Consequently the Empire went through a series of crises, in which the succession to a previous, usually dead, emperor was the main issue. The infamous ‘Year of the Four Emperors’, AD 69, is only the most famous of these crises, which often involved bouts of bloody and destructive civil war, assassinations and purges. These were followed by a period, usually relatively short, in which the victor in the ‘crisis’ established a new system, juggling the three basic elements identified by Augustus, but which was as fragile and short lived as its predecessor; these ‘consequences’ of each crisis are discussed. The lucid and erudite text is supported by numerous genealogical tables and dozens of depictions of emperors.