Age of Empires II: Definitive Edition (PC) - Achievement - Bounty Hunter
Convert at least 3 Byzantine generals in "The Emperor's Revenge".
To win the mission, you must kill / convert 5 Byzantine generals. As long as at least 3 out of the 5 generals are converted, the achievement will trigger. Near the start of the game, your spies reveal the locations of these generals. Just be careful not to kill them with your troops accidentally. Building a Fortified Church in the Armenian Villages (Grey) is a secondary objective, but ties in well with producing Monks for this purpose alongside Warrior Priests and helpful upgrades for them to make this easier.