I don't think that's actually a Carroccio. But if it was, that's exactly where you would expect the professional soldiers that had existed for a long time -- the permanent guards that were hired even by the republics (they're basically the equivalent of "household" guards -- I'm not sure if there's a better term). Also that's where the important nobles and politicians would also be there. But, I'm pretty sure it's not a Carroccio. Not sure what it is -- I know there were experiments with war wagons and carts, but little more than that.