The Tomed Incident was an unspecified confrontation between the United Federation of Planets and the Romulan Star Empire in 2311, costing thousands of lives. (TNG: "The Neutral Zone")
The incident led to the signing of the Treaty of Algeron, and the removal of the Romulans from the affairs of the Federation for many years, probably until 2364. (TNG: "The Pegasus")
- The Tomed Incident was the primary focus of the Lost Era novel, "Serpents Among the Ruins".
- The exact length of time of the Romulan isolation has been retconned several times during the production of TNG and later series and movies. In "The Neutral Zone", Data stated it were 53 years, seven months and 18 days since the last official contact between the Federation and the Romulan Star Empire.