Additionally, the Isibongo feature of the Zulu gives a +3 Loyalty bonus to cities with garrisoned units, up to +5 if those units are Corps or Armies, and capturing cities with a unit automatically upgrades them to a Corps (or Army). Basil Ii's unique ability, Porphyrogénnétos, allows Heavy and Light cavalry units to deal full damage against cities following the player's religion and unlocks the unique Tagma unit, a Medieval-era Knight replacement that gives nearby units +4 Combat Strength. This governor has diplomatic and military bonuses that provide bonuses to military unit production, defensive combat strength bonuses, and unique abilities or bonuses based on where the Governor is placed in a captured capital civilization.