Any ideas on how to deal with an enemy grand battery that is ripping your defensive line to shreds? They have two batteries to my one, and I have no cavalry in that section. Do I just have to do a mad charge at the guns at some point?
Difficult to say without having a graphic, but it is probably more effective to step back, preferably into cover, or behind cover.
Take some effort for him to bring up the Grand battery again, and at least it is one card less to be used shooting at you.
The other solutions might be
1. Bring cavalry across
2. Attack in another section to distract attention elsewhere.
The ideal would be to combine those two, where your cavalry carves it's bloody way across to threaten the grand battery.
Glory is fleeting, but obscurity is forever.
I agree with what Mark says below. A "mad dash" with infantry can really backfire. If you don't get enough hits on the arty, the battle back will kill you, especially if he has a first strike, or Artillery Canister tactician card and can roll first.
Depending on terrain and with the right cards, you may be able to flank the battery - only allowing 1 to shoot at a time due to line of sight restrictions.
I usually take out enemy artillery with heavy cavalry with a cavalry charge card and/or combined arms. An artillery unit all by itself is very vulnerable, but when it is supported and/or with a leader it is very difficult. With no cavalry, only infantry, you need a force march card and a infantry leader forward tactician card and try to overwhelm the artillery. Have your shooters combat first and melee last. A short supply tactician card comes in handy too.
One side having more artillery than you can really unbalance a game. Good luck.