In my new, slower Pergamon game, I've still got just Mysia in 259BC. Just concluded a war with the Seleukids; at the beginning of the game I'd switched Epeiros' default alliance with the Ptolemies to the Seleukids, and they'd ignored me for the longest time. Within a few seasons of breaking the alliance, they attacked. I defeated several armies, took Ipsos and Sardis and destroyed the military infrastructure (barracks and blacksmith), then walked away. While I don't like the impact of destroying barracks on army compositions, I'm not going to be advancing in that direction (or any direction, for that matter) for a long time, so hopefully by the time things kick off again, they'll have rebuilt proper barracks. Plus stops them depleting their local populations in the meantime.