Soon after Postumus seized power, Gallienus marched against him, but was wounded by an arrow and forced to withdraw. This secured Postumus’ position and, in the winter of 260/261, he may have traveled to Britain, an event possibly depicted in some of his coins. At any case, by 261 both Britain and Spain had joined his cause, along with Gallia Narbonensis.in wikipedia
After the defeat and death of Macrianus Major and his son Macrianus Minor in Thrace, the legions and governors of the eastern provinces deserted to Odaenathus of Palmyra, who had officially remained loyal to Gallienus. Quietus, the young remaining son of Macrianus Major and still a would-be-emperor, fled to Emesa with the prefect Ballista, but was killed by the inhabitants of that city. Acknowledging Odaenathus’ position, Gallienus granted him the titles of Dux Romanorum and Ruler of the East.in wikipedia
Following the collapse of the Macriani, their supporter, the Egyptian governor Lucius Mussius Aemilianus, proclaimed himself Emperor in Thebes in late 261. His reign proved to be brief, and by the end of March 262 he had been defeated by Gallienus’ general Aurelius Theodotus. Theodotus immediately took over the governorship of Egypt, sending the captive Aemilianus to Rome, where he was strangled in prison.in wikipedia
In early 262 or possibly late 261 an earthquake or sequence of earthquakes struck the east-central Mediterranean. The damage was particularly severe in the Roman province of Asia, especially around Ephesus, but Rome and Libya were also shaken. Many cities were flooded by the sea, presumably due to a tsunami caused by the earthquake, and the disaster was made worse by a renewed outbreak of the plague.in wikipedia
In 262 a branch of Goths invaded the Roman province of Asia, where they sacked Ephesus and plundered and burned the famous Temple of Artemis, one of the Seven Wonders of the World. They remained at large for much of the year, but were eventually routed by Roman forces and withdrew to their northern homelands.in wikipedia
In spring 262, with the backing of Gallienus, Odaenathus of Palmyra attacked the Persian garrisons still in occupation of Edessa, Carrhae, and Nisibis and drove them from the Roman Empire. The Palmyrene–Roman forces then crossed into Persia, sacked Nehardea, and, in late 262/early 263 besieged the Persian capital Ctesiphon. However, Odaenathus was unable to capture the city in the face of Persian reinforcements and eventually withdrew with many prisoners and much booty. The Roman border fortress of Dura-Europus, destroyed by the Persians the previous decade, was left abandoned.in wikipedia
Shortly after Aurelius Theodotus arrived in Egypt and brought an end to Mussius Aemilianus’ usurpation, a second rebellion broke out under Memor. Memor was of Moorish origin and in charge of the vital Egyptian corn supply, but was swiftly killed by Theodotus, even before he could be proclaimed Emperor. With Egypt now pacified, Gallienus made Theodotus prefect.in wikipedia
In 266, with the likely backing of Gallienus, Odaenathus launched a second invasion of the Persian Empire. He reached as far as Ctesiphon, and according to some sources captured it. However, news of the Gothic and Heruli invasions in the Aegean persuaded him to end the campaign and march for Anatolia.in wikipedia
