"Kill the Overseer who led the slaves" is an optional mission objective in Lifting The Veil in Freedom Cry
Walkthrough[edit]
When you have finished the second Eavesdrop, take out a Soldier or Captain and take their weapon. Head to the front of the mansion and go over to the left-hand side. There, using Eagle Vision, you can locate the Overseer who led the Slaves. Move in and kill him with the stolen sword.