This is the only fully illustrated military life of the Emperor Publius Licinius Egnatius Gallienus (253-268). Considered the most blatantly military man of all of the soldier emperors of the third century, Gallienus is the emperor in Harry Sidebottom's bestselling Warrior of Rome novels. Gallienus faced more simultaneous usurpations and foreign invasions than any other emperor, but somehow he managed to survive. Dr. Ilkka Syvanne explains how this was possible. It was largely thanks to the untiring efforts of Gallienus that the Roman Empire survived for another 1,200 years. Gallienus was a notorious libertarian, womanizer, and cross-dresser, but he was also a fearless warrior, duellist and general all at the same time. This monograph explains why he was loved by the soldiers,yet so intensely hated by some officers that they killed him in a conspiracy. The year 2018 is the 1,800th anniversary of Gallienus' date of birth and the 1,750th anniversary of his date of death. The Reign of Gallienus celebrates the life and times of this great man. AUTHOR: Dr Ilkka Syvanne gained his doctorate in history in 2004 from Tampere University in his native Finland. His doctoral thesis was published as The Age of Hippotoxotai, Art of War in Roman Military Revival and Disaster 491-636 (Tampere UniversityPress, Tampere 2004). He was the Vice Chairman of the Finnish Society for Byzantine Studies from 2007 to 2016. In 2017 he was nominated as an Affiliated Professor of the University of Haifa. He contributed to The Encyclopaedia of the Roman Army (Wiley-Blackwell, 2015). The first volume of his Military History of Late Rome series was published in 2015 and Caracalla: A Military Biography in 2017, both by Pen & Sword Books. He lives in Kangasala, Finland. 120 colour and b/w illustrations, 35 b/w maps