Your artillery has a medium range, so you must get it semi-close. It can still fire far enough away to where the enemy has no chance of hitting you unless they have a missle launcher. Try using your probots scan ability so it won't be in harms way.
There are tactics to use artillery all over place, you just hav to find the right one for you. Hopes this helps out a little.
Sacrifices are necessary for the ultimate goal.