Events By Place Roman Empire Gallienus becomes Emperor. Gallienus defends what remains of the empire against barbarians and usurpers. He reorganizes the army and reforms the administration. Gallienus reinforces the military and establishes a new mobile force supported by the cavalry, which becomes the pivot of the Roman army. The army's headquarters are established in Milan. The Roman fort of Wiesbaden (Germany)'s captured by the Alamanni (possibly 259). Franks take control over the Schel… (More on 260)