Stealth mode is a mode available to certain units in Age of Empires III. In this mode a unit becomes invisible to the enemy but can still be seen by the user. While in this mode, units are considerably slower than normal. When the technology Spies is researched a player can see other player's stealth units. Spies [not the technology the unit] are able to see other stealth units as well as being able to go into stealth mode themselves. The Jaguar Prowl Knight and the Forest Prowler are some of the most effective units in stealth mode due to the fact that they can be used in large groups. The Sioux War Chief has the ability to be stealthy if a certain Home City Card is sent. Stealth mode can be used to sneak up on the enemy to ambush them or do a surprise attack.