The Roman Empire From Severus To Constantine 2nd Rev Ed 2004 2nd Revised Edition 2004 Pat Southern by Pat Southern 9780415239431, 0415239435 instant download after payment.

I find Southern’s writing to be clear and understandable ---very well-crafted. I found the author’s well-developed bibliography particularly helpful. Passable maps, interesting illustrations and the obligatory, colossal head of Constantine accompany the text as well as a number of numismatological sketches of the era’s coinage. 

Chester Starr in his brief but excellent THE ROMAN EMPIRE delineates this time period as « The First Test »---a massive turning point for the empire. Southern does a masterful job examining the evolving threats to the empire including themes such as depopulation, barbarization, succession, usurpation. I also liked her analysis of the mobile, multiethnic war bands of the era as well as her defense of the Emperor Gallienus (not too surprising as she co-authored THE ROMAN CAVALRY). I thoroughly enjoyed this work, in all three readings. 

I recommend following this up with Birley’s SEVERUS and William’s DIOCLETIAN. The old standby, AMMIANUS MARCELLINUS, is still available in an affordable Penguin abridgment.