Tomed Incident
From Star Trek : Freedom's Wiki
The Tomed Incident was a terrible confrontation between the United Federation of Planets and the Romulan Star Empire in 2311 that cost thousands of lives. The incident led to the signing of the Treaty of Algeron, which banned Federation research into or use of any cloaking device, and the withdrawal of the Romulan government from interstellar affairs until 2364
