After the Vulcans refusal to fight against the Romulans in the war they installed warp detection grids in all of the Coalition's systems. However, the Romulans discovered a way to circumvent these systems, allowing them to surprise unsuspecting Starfleet ships.
The USS Yeager was on patrol near Deneva when Romulan vessels entered the system and attacked the Yeager. The attack took Yeager entirely by surprise and led to it's destruction. Then, a short time later, the Tellarite warship Miracht entered the system and was engaged by the Romulans who attempted to take over the ship with their remote capture device. In order to stop the Romulans from capturing one of Tellar's strongest warships the ship's captain, Prev, fired a weapon into the ship's warp core, destroying the entire ship.
After the Romulans took out all space defenses, they landed troops on Deneva. The MACO contingent attempted to defend the planet, focusing on the capital city, but the Romulans' superior numbers overwhelmed and wiped out the defenders. Few people managed to escape the planet before it fell.
This was the first major loss for the United Earth, with a major colony world being lost. It also showed that the Romulans managed to find a tactic to elude the warp detection grids installed by the Vulcans. (ENT - The Romulan War novel: Beneath the Raptor's Wing)
|Battles of the Earth-Romulan War (2155-2160)|
|Prelude||Devastation of Coridan III • Battle of Draylax • Battle of Alpha Centauri • Battle of Calder II • Kobayashi Maru Incident|
|2155||Battle of Tarod IX • First Battle of Deneva • First Battle of Berengaria • Skirmish near Threllvia IV • Fall of Threllvia IV • First Battle of Altair VI|
|2156||Battle of Andoria • Invasion of Capory • Mission to Aeihk'aeleir Shipyard • Invasion of Draken IV • Second Battle of Berengaria • Battle of Algeron • Ambush in the Onias sector • Second Battle of Altair VI • Battle of Tau Ceti IV • Second Battle of Deneva|
|2157||Battle of Gamma Hydra • Battle of Galorndon Core • Battle of Prantares|
|2159||Search for the Seleya • Attack on Gravenor • Mission to Epsilon Theta • Mission to Encaria • Battle of Tyburn • Third Battle of Altair VI • Battle of Vorkado • Third Battle of Deneva • Battle of Beta Virginis • Battle of Delta Pavonis|
|2160||Battle of Tenebia • Devastation of Draylax • Attack on Sol • Battle of Cheron|