This Capital City is Lv. 3, so it naturally has 8. There are 3 Serfs, 1 Warrior, and a Paladin (has a bonus ability) in the Courtyard and Action Bar, so together with bonuses they have 10. A Sea Vessel docked on the Shore Region has 3. The 3 Serfs on Buildings' Worker Spaces together have 3.
Therefore added togehter, the total Strength of the Capital City before Tactic Cards are chosen is 24.