Combinated attack with 2 Artillery units ?

Can we play combinated attacks of this kind ?
For myself, I think it possible.
Greetz from Le Mans

It is a basic rule that combat is done one unit at a time unless it is a Combined Arms combat so I do not think you can fire two artillery units simultaneously on one target. So the Grand Battery tactic must be done one artillery unit at a time.

At least that is my understanding.

A combined Arms attack must be led by an Infantry or Cavalry unit in melee.
There is no limit to the number of Artillery units that may join in, other than available orders, but you can not initiate a combined arms attack consisting of just 2 artillery units with no Infantry or Cavalry involved.

Thanks for your responses...
Been tired these days having flu and it had "smogged" my brain...