Battle of the Omarion Nebula

The Battle of the Omarion Nebula was a battle between a joint Romulan Tal Shiar/Cardassian Obsidian Order task force and a Jem'Hadar fleet in the Omarion Nebula.

The strike was intended to preemptively attack the Founders' homeworld but ended as a horrible defeat for the forces of the Order and Tal Shiar, leading to the disgrace of both organizations. (, SS ST (Twilight's Wrath))