Land and Sea military units have a Zone of Control, which extends to all 8 adjacent tiles. No unit can move from one tile within a Zone of Control belonging to another player's unit, with the exception of assaulting. That means, if you move straight-on into the tile adjacent to any military unit, you will have either to double-back, wait, or assault that unit. If you happen to be surrounded by three or more military units, any movement (except for assaulting) will likely be impossible. In addition, a unit which has a Zone of Control blocks any resource gathering from the tile it occupies (except by friendly <l:6,98>workers<e> of course). <l:6,69>Allied<e> Civilizations mutually ignore their zones of control. Note that Air, Space and <l:6,120>Stealth<e> units both do not have Zone of Control and ignore enemy Zones of Control.
- A tile that as a friendly unit on it is always considered exempt from enemy ZOC's.
- Same with a tile that the enemy unit cannot enter (land tiles against sea units and vice versa, mountain tiles against <l:1,88>Tanks<e>, deep ocean tiles against <l:1,108>Triremes<e>).