The Irish wars
We have a rather pathethic monarch with crappy skills. As we can't depose of him we turn him into a military leader and send him of the battlefields. Hopefully he takes an arrow to the knee and dies.
Turns out he is a pretty ok military leader though. He crushes the Munster troops. At least that's some good use for him as he has pretty good survival instincts and he lives a long and happy life as king and commander.
We take munster
We take Connaught
