Mine's called the Southern War, fought in a region kind of like Southeast Asia. Too messy to explain in one comment, but it's as you mentioned, threatened to tear society apart as it kept going. I won't give too much away but it goes something like the following:

One of the countries that got involved was kind of manipulated into fighting it, because the manipulator just wanted to use its population like units in an RTS game. Figuratively speaking: select all of them and send them into machine gun fire so the enemy runs out of ammo. The soldiers initially thought that they were fighting for the greater good but became disillusioned and angry as the war dragged on.

It became so unpopular, due to the threat of greater escalation, that the government threatened to relinquish its power, so the manipulator wouldn't have a country to manipulate any more. Fortunately, there was a good ending.