If one artillery fires, and after it attacked a halt order is given. the arriving 28 artillary (still to fire) joins the halted artillery and loses its attack chance. This should be fixed!
You have to keep it seperate from the arti yet to fire, if you want them to get their legit shot.
This is just a way to prevent abuse where delay command can be used to join an attack every 2 mins, there by attacking every 2 mins.
By placing them at a distance of each other, they are different armies, and so they risk themselves being closer to the enemy.