I've tried all kinds of setups, infantry with support from artillery, 40% inf 40% art 10% eng 10% cav, cavalry heavy with some infantry and some artillery and more but no matter what I get crushed even when I fight pure mobilized stacks with worse tech even though the terrain isn't that bad and the generals are about equally good. I always go for about 10 regiments, although sometimes I use 12. What do I need to do to win battles without having to do the deathstack and retreat to reinforce tactic? It's worth noting I have the Concert of Europe mod which influences how good some techs are.