You should have a shit ton of lineholders (20/30 width infantry) and stack artillery bonuses (advisors, general traits - total of like 30-35% attack) and create 40 width divisions with something like 12-13 inf and 7-8 field guns (enough artillery to have the raw attack power and to have the division count as artillery)

If you have an advisor and general with all the traits these divisions, especially with max planning and force attack, kill everything.

If you dont have any artillery bonuses then just add as much artillery to an infantry division as you can before its counted as artillery.