Leadership bonus of Chief Warlord applies to all units of their capital.Erf-b1-p040a Having the Chief Warlord in the same hex adds another bonus. Units in the stack led by Chief Warlord get yet another bonus.Erf-b1-p113
Known Leaderships & Comparison
10 - Prince Ansom Erf-b1-p145 Since Prince Ansom was put in charge of the Royal Crown Coalition forces for Battle for Gobwin Knob, it's not hard to imagine that level 10 is the maximum. Plus, ya know, it's a ten. Are they going to crank it up to eleven? We don't know.
"Leadership" can also refer to a either a single leader or group of leaders such as Warlords or Casters. Gobwin Knob sought to target or "hit" the leadership of the Royal Crown Coalition to deny RCC forces leadership bonuses. They were successful when they hit RCC Leaders Duke Nozzle and the Blue Warlord.