It all comes down to scouting. Stay within your province count and you can battle with ease, even if you are in a higher level chapter.I have given up long ago on battling period. At the start of the game winning battles was easy. It quickly became impossible, as the squads were always out numbered. It puts a big ugly dent in the game.
Battling is not so much of an issue, even if you are clueless about it. It is possible to outnumber the enemy and win very easily on autofight