By 268 A.D. a Gothic War was underway. The Goths had warmed up by attacking along the Danube in the 262-263 timeframe and then ravaging Asia Minor in 267. Joined by the Heruli tribe, they raced down the Balkans in 268 and sacked Athens. Gallienus blocked and defeated them at Naissus, but was recalled to Milan to put down an internal revolt. While there, he was assassinated.
The next emperor, Claudius II “Gothicus” made his living fighting the Germans. He defeated the Alemanni, after they crossed the Alps in 268 A.D, and then campaigned against them again, with success, the next year. The Goths achieved a partial victory against him in 270, but were laid low by the plague. The emperor also contracted the disease and died in August of 270.