Oh, you mean like how Flaminius showed mercy to the armies of Philip V?
As for what to do, I agree with Vasiliyi - the Romani do not back down. They would never surrender, and when that army was destroyed, they would build another one. Also, I'd recommend fighting that Epeirote army sooner rather than later - that way you can take more of them with you and hopefully there will be fewer to fight when you send your next army. -M
Bookmarks