I found the horse artillery a little annoying with the 'limber' / 'unlimber' although this might have been my comp being slow and me basically clicking it two many times which cancelled the action and meant they sat there doing nothing.

HOWEVER, on the three times I've run the land battle each time I have engaged the US troops with line infantry (I had smaller numbers) held my own due to my troops being better and then moved the horse artillery into the flank and raked them with canister. Almost instant rout and your cavalry can easily mop up the troops once they're running. Won each battle losing around 400 men. Not ideal but just wanted to see each units capabilities.

The American artillery is powerful, although seems slower to load. I wait for them to fire then rush the cavalry in to skewer them while they can't fire back - thankfully the artillery aren't as heroic hand to hand as previous games and usually die without a prolonged fight.