Oh look I lied, this artillery battery has an 8-Inch Howitzer and Coehorn Mortar in addition to its two Garrison Pieces. See what I mean about Fort Ligonier not hurting for artillery pieces? Other starforts would kill for a few of these guns. From that sign there at bottom left:

Similar to a ship's cannon, this six-pounder, lacking mobility, can only be used in a battery. An elevating wedge raises and lowers the barrel. It shoots six-pound solid shot, grape shot or canister.