ORIGINAL: balto
Explorminate, not sure I get what you are saying and I do not know what a Heavy Siege Corp is, but wouldn't it be easier to just use Strategic Redeploy or Move your Infantry into the woods and the Heavy Siege stuff (assuming it has lots of equipment.., mechanized, maybe) to the area where you want it?
But still back to the original question, I think Das is supporting me in this - in that, does a mixed unit fight with all units when DIRECT is used. Because presently, many are using the INDIRECT command with their mixed units because they believe the arty does not behave like arty if you click the DIRECT button, simply because there is a button for INDIRECT.
Please, call me Ben or BATTLEMODE, eXplorminate's the site I do some work for
Ok so I posted some info above on what constitutes a Heavy Siege Corp, including specific numbers of men and artillery equipment. It's not motorised (that'd be useless in Heavy Woods anyway as that terrain has a big penalty to wheeled units). Each counter contains some infantry, and some guns. That formation can attack either direct or indirectly at range (but only to adjacent hexes as it has a range of 1, same as a standard non-ranged unit).
The short answer to your question is yes. When you attack directly with a combat unit that contains artillery they will also take part in the battle, fire and do damage along with whatever other troops or equipment are partaking in the battle. You don't have to click "indirect" because that is a different attack type, and activating that stops enemies without artillery engaging you, at the expense of stopping your own non-ranged units attacking.
Does this answer your question?