Seriously mate. Engage brain before posting.
Look at the average size of an artillery formation. I have no idea, but I suspect that it has to be a lot less than 50k men. Then look at the hex size. Got any idea how big those hexes are? No, neither do I, but you'd lose the entire Allied artillery in just one of them. Then think about the range implications - either they have hugely unrealisitic ranges or they have to go toe to toe with frontline infantry units to engage them.
Anyway, they're incorporated in the existant army and corps (and probably tank) formations. As they would have been in real life.