The USS Sempach was a Constellation-class Federation starship that was in service in the late 23rd century. She was launched in 2275, under the command of Commodore Jono Danilov, and was only the second Constellation-class vessel to be launched.
In 2276, the Sempach was one of six Starfleet ships that met with a Romulan flotilla for peace talks under the protection of the Lalairu city-ship Mascrar. The other Starfleet ships were the Constitution-class ships: USS Enterprise under Captain Kirk; USS Ortisei, under Captain Harold Gutierrez; the USS Hemalat under Caitian Captain Hressth ssha-Aurrjjesh; the USS Lake Champlain, under Centauri Captain Finn Winter; and the USS Nimrod. Also present was the renegade Romulan warbird ChR Bloodwing under former Commander-General Ael t'Rllaillieu, who had stolen the Sword of S'task from the Empty Chair in the Romulan Senate.
The Romulan flotilla consisted of the new, all-Romulan design heavy cruisers ChR Gorget and Thraiset, the K't'inga-class cruisers ChR Pillion and Hheirant}, and two other vessels, the ChR Satieh'lill and Greave. The Gorget was where all the senior Romulan ambassadors were quartered, including hero and popular common people's senator, Arrhae t'Khellian.
The peace talks turned out to be a cover for the Romulans' second attempt to destroy the Bloodwing in an effort to reclaim the lost Sword. The Pillion had snuck in another cloaked vessel which later decloaked and attacked the Bloodwing, though it was destroyed before it could succeed and the ship's torpedoes mistakenly destroyed the Romulan ship Thraiset.
The Romulans having broken the truce by firing first, the Lalairu joined with the Starfleet ships to rout the Romulans. The Mascrar destroyed the Satieh'lill, the Sempach destroyed the Hheirant, making three Romulan ships confirmed destroyed, and the Gorget escaped.
Starfleet casualties included the destroyed Lake Champlain, the badly damaged Ortisei which had to be evacuated, and the Hemalat which took a primary hull hit that knocked out their warp capacity. The Sempach survived the engagement unscathed. (TOS novel: Honor Blade)
|Constellation-class class XII heavy cruiser/exploratory cruiser starships|
| Federation Starfleet|
|standard heavy cruiser configuration||Andromeda • Antares • Antietam • Aquarius • Betelgeuse • Callisto • Canopus • Ceres • Cochise • Constellation (I) • Constellation (II) • Constellation-D • Diadem • Effros • Eridani • Fading Sun • Ferrel • Gibraltar • Gihlan • Indiri • Leonid • Libra • Minora • Nebula • Nova • Orion • Pisces • Polaris • Pulsar • Sagittarius • Sempach • Sirius Major • Speedwell • Stargazer • Taurus • Tubman • Valkyrie • Vespucci • Victory|
|variant heavy destroyer configuration||Alaska • Anatevke • Asakaze • Baccarat • Cassiopeia • Constance • Daring • Diamond • Dragon • Fabrizi • Gettysburg • Hamner • Hathaway • Hollister • Keppler • Leningrad • Magellan • Malign • Marceau • Meredith • Mitisio • Norris • Rupertus • Tai Kang • Taussig • Volkov • Whirlwind • Zodiac|
| Terran Imperial Starfleet|
|Starbreaker • Stargazer|