I've been wondering about this ever since the vanilla Civ V. Just what is the upside of Pledge To Protect a City State? I've never seen anything on this, and after Searching the Civiliopedia as best I could, I couldn't even find a reference to it, much less just what it is that you get by making such a Pledge. I would _imagine_ that by pledging you would gain some Influence, or perhaps shift the Influence base point for as long as the Pledge is in effect. But I've never seen that confirmed. It also seems to me that _failure_ to uphold the Pledge by declaring war on an attacker, or donating units to the CS in question, would result in a sharp LOSS of Influence. Not just with that CS, but pretty much with ALL CSs, because you have demonstrated just what your Pledges are worth. But once again, I've never seen any confirmed details as to how the mechanism works.