On this day in 629, the Roman emperor Heraclius entered Constantinople in triumph. He had finally accomplished what no other Roman emperor in history had been able to do: he decisively and permanently defeated the Persians, ending the war that had been going on more or less continuously for more than six centuries. Curiously, seven years later, Heraclius would lose most of the Empire to the advancing Muslim Caliphate. He was versatile, this Heraclius.