From Gladiator to Rome Total War to I, Claudius, today the Cohortēs praetōriae are one of the most distinctive military units of Imperial Rome. It was their job to protect the Roman Emperor and his household, a task for which they hold a somewhat ‘chequered’ record (especially when we focus in on the Praetorian Prefects). But what do we know about this unit’s origins? How did this powerful force become protectors of the Emperor and his household? What other functions did they serve? And how did they differ from the standard Roman legions in their structure?

To talk through the rise of the Praetorian Guard, with a specific focus on the reigns of Augustus and Tiberius, Tristan caught up with historian Lindsay Powell at Fishbourne Roman Palace in West Sussex. Lindsay is the author of several books about the Early Roman Imperial Period. His latest book, Bar Kokhba: The Jew Who Defied Hadrian and Challenged the Might of Rome, is out now.