Romulan cloaking technology has been a reoccurring feature of the Star Trek universe ever since it was first described in this episode.  Dangerous and unethical, the ability to cloak ships would give the offending party an unfair advantage in war, as well as the ability to carry out espionage without detection.  It was up to … More Cloak and Swagger, TOS: S3E2 “The Enterprise Incident”