Many combat units exert a "Zone of Control" (ZOC) influence over the tiles around them. Combat units that enter an enemy's ZOC must stop, regardless of any remaining Movement. Units that have been stopped by an enemy's ZOC have the option to attack if they have the required Movement to do so.
Ranged and Bombard class units do not exert ZOC. Cavalry units, as well as Naval Raider class units have the ability to ignore an enemy's ZOC.
Religious units exert ZOC against other religious units.
Rivers block Zone of Control from all units.
Zone of Control
Many combat units exert a "Zone of Control" (ZOC) influence over the tiles around them. Combat units that enter an enemy's ZOC must stop, regardless of any remaining Movement. Units that have been stopped by an enemy's ZOC have the option to attack if they have the required Movement to do so.
Ranged and Bombard class units do not exert ZOC. Cavalry units, as well as Naval Raider class units have the ability to ignore an enemy's ZOC.
Religious units exert ZOC against other religious units.