In Total War: ROME II, visibility of enemy units depends entirely on what your own units can see at any given time, so, if the enemy are hidden by a building or the terrain itself, they may not be visible to your forces. By the same token, enemy units may disappear during a battle if they pass out of view of your troops. An eye icon appears above your unit when it is hidden or when it is out of the enemy’s line of sight. It will disappear when your unit has been spotted by the enemy. It’s also important to note that visibility is entirely separate to the hiding attribute. Although deployment enables the secret deployment of most units, ships and siege equipment cannot be hidden from the enemy due to their size.