The Drill Grounds provides capacity for your army's units. Its unit display separates troops in the base from those outside, so a deployed march is still part of the army you manage here.
The first plot requires Base level 7. Additional plots expand this part of your base, with their own construction requirements.
How unit capacity works
The Barracks trains units, but the Drill Grounds determines how much room you have for them. When its limit is reached, unit transfers can be blocked. Items that would put you over capacity also trigger a warning.
This capacity is different from Hero Squad Size and march slots. Hero Squad Size concerns units within a formation; another Squad gives you another march to deploy.
Capacity differs by plot
The first Drill Grounds starts at 1,000 Unit Qty. At levels 10, 20 and 30, it provides 3,000, 5,000 and 7,000 respectively. The additional plots start at 2,000, so identical building levels do not mean identical capacity across every plot.
Drill Grounds Expansion research also affects capacity. The Hospital has a separate capacity for injured units and its own healing controls.
See Troop Training, Promotion and Healing Explained for how these systems work together.
