“If they had known all of the details, there is no way the anti-gunners would have chosen this field to fight their battle. But they couldn’t know, because they fully committed in the first thirty minutes. That’s the problem with rapid-reaction plans; they are by their nature generic, and they can’t be adapted to the situation.”
If you haven’t read the history of the first few months of WW I, that’s just what happened then.
No plan of battle survives first contact with the enemy.