Is diplomacy necessary?

In general, diplomacy would be quite helpful if it could at least bring the morale up to zero, while you have a large number of troops of the highest level. And also, the Shackles of War! By the way, it's a good artifact because the AI is a jerk and constantly retreats when it sees that things are going badly, but before a battle, you can almost always check whether it's worth putting these chains on yourself, or you might end up making things worse.