There are Generals available in the Store and during some events that increase Carrying Capacity to 220(Master of Martial Arts & General Log), 250(Veteran General), and 270(Major General). There is also a Quarter Master General which has a unit capacity of 1000, but it is transportation only(no fighting capabilities).
Sorry, I misread your post. I didn't see the garrison. The two posts above this one are correct. Mine was not.
If something can go wrong, it will.