"McDonald's Rule" broken
Apparently, Beirtut has a McDonald's (it got bombed in 2003). And McDonald's Israeli subsidiary "operates more than 80 restaurants across Israel." And Israel is certainly at war with Lebanon. I suppose you could argue that Israel is at war with the stateless entitiy Hezbollah, and then argue whether or not Hezbollah has any McDonald's, but when Israel is bombing the Beirut airport and blockading ports, that's war with Lebanon as far as I'm concerned.
So the rule has definitely been broken. Not even Happy Meals can stifle Middle Eastern violence.
Of course, the McDonald's rule has been broken before, as early as 1989 when the United States invaded Panama. So I guess Ronald McDonald isn't perfect at keeping the peace. But I bet his record is pretty good when compared to NATO or the UN. (Of course, NATO and the UN take on tougher jobs.)