Stealth mode is a special ability introduced in Age of Empires III: The WarChiefs. Available to a limited range of units, activating this mode renders the unit invisible to enemy Line of Sight (LOS). While in this mode, units move at half their normal speed and no longer engage enemy units automatically. They will abandon stealth mode if ordered to attack by the player.
Units cannot switch to stealth mode if enemy units or buildings are nearby.
Some units and buildings have the Sees Stealth tag and will uncloak stealthy enemy units within their LOS. Not all stealth units are also anti-stealth. Notable anti-stealth units include virtually all Heroes and Explorers, Forts and Town Centers.
When Spies is researched, the player can see other players' stealth units whether they're in stealth mode or not.
List of stealth-capable buildings and units
- War Hut (Incas, with Cloud Fortresses Home City Card)
- Stronghold (with Cloud Fortresses Home City Card)
- Lakota War Chief (through the Center of Power card, keeps his normal speed when stealthy)
- Sohei Archer (through the Monastery upgrade Intonjutsu Stealth)
- Eagle Scout
- Native Scout
- Navajo Rifleman
- Coyote Runner (through the Silent Strike card)
- Shinobi (only loses a quarter of his speed)
- Forest Prowler
- Jaguar Prowl Knight
- Tashunke Prowler
- Chimu Runner (through the Cloud Warriors card)
- Jungle Bowman (through the Cloud Warriors card)
List of buildings and units that can uncloak stealthed enemies
- Town Center
- Agra Fort
- King's Hill
- War Hut
- Nobles' Hut
- Regent's Castle
- Asian Outpost
- Native Scout
- War Dog
- Explorer Dog
- Mongol Scout
- Hot Air Balloon
- Advanced Hot Air Baloon