I lost an entire corp in one turn. I was attacking a corp sized force inside Ft. Monroe. My corp was fully supplied on normal/normal orders (orange/orange), and I attacked by land from the Chickahominy river region. The first round was a draw, we fought again another day, then another day, and so on seven times in 15 days. My force started to lose badly but would not retreat to another region. At least 30 infantry regiments were destroyed completely because they were still attacking with no cohesion.
I think what happened is this: I sent a fleet of ironclads back and forth seven times through Hampton Roads with bombardment orders. I think each time the fleet bombarded it compelled the land forces to attack.