Cloaking Device:  2260's

The Romulans developed the cloaking device, or practical invisibility screen, in the 23rd century.  This device could render their ships invisible to the naked eye and conventional sensors, offering the Romulans a massive tactical advantage over their opponents.

The early version of the cloaking device had serious limitations - it required massive amounts of power, meaning that the ship in which it was fitted could only travel at minimal speeds.  As with almost all the subsequent versions, the ship needed to decloak to fire its weapons.  The cloaked ship also had to maintain a communications blackout to avoid detection.  In 2266, the Romulans decided to test the cloaking device by sending a cloaked Romulan Bird-of-Prey across the Neutral Zone to attack several Federation outposts.

Captain James T. Kirk, in command of the Starfleet vessel, U.S.S. Enterprise NCC-1701, discovered that the sensors were able to detect the Romulan vessel when it was moving, though not accurately enought to establish a weapons lock, Kirk used this limited advantage to pursue the Romulan commander, and managed to destroy the ship before it could escape to Romulan space.  Not long after, the Romulans and the Klingons briefly joined forces and exchanged a significant amount of technology.  This alliance produced an upgraded cloaking device that rendered the ship completely invisible, and also worked at warp speeds.  The technology was so effective that the Romulans were unable to detect their own vessels when they were cloaked.

This model of cloaking device was fitted to Klingon-designed battle cruisers, which were far larger than Bird-of-Preys. The Federation took the threat posed by this new cloaking device very seriously, and mounted a covert mission to steal one.  The cloaking device itself was a portable unit that could be fitted to the main deflector of a vessel in a matter of minutes.  Cloaking technology has moved on since the 2260's, with each side making major advances in detection and cloaking techniques.  In practice, the Romulans have always managed to stay one step ahead

Starfleet has not attempted to develop its own cloaking technology since 2311,; when the Federation and the Romulans signed the Treaty of Algeron.  This peace accord specifically forbids the Federation from pursuing cloaking technology, and has kept the peace for 64 years.

The cloaking device of the late 2260's was approximately one meter long, consisting of a large glowing sphere above a circular base and a cylindrical unit that protruded from the top.  It simply plugged into a bay on the vessel, connecting it to the deflectors and rendering the ship invisible to sensors.  On Romulan vessels, the room containing the cloaking device was a secure area, and personnel could only enter if they had the necessary clearance.  The room was crewed at all times, with a guard posted in the corridor outside.  The mission during which Captain Kirk stole the Romulan cloaking device was significant, since it allowed Starfleet to examine the technology and maintain the balance of power.