Battle of the Omarion Nebula
The Cardassian Obsidian Order and Romulan Tal'Shiar were concerned with the growing Dominion threat. They decided to destroy the Founders' homeworld and remove the threat. Federation intelligence did not assist, although they knew of the plan. They allowed it to proceed, believing Tain's plan had a fair chance of success.
The Dominion knew of the plan as well, and infiltrated a Founder to assume the identity of Colonel Lovok of the Tal'Shiar.
Twenty Romulan D'deridex-class warbirds and Cardassian Keldon-class cruisers using Romulan cloaking devices entered the Gamma Quadrant under cloak. The allied fleet scanned the surface of the planet, and determined there were no enemy forces in the area. Tain ordered his fleet to drop their cloaks, then gave the order, "So much for the Dominion... open fire!"
A Romulan officer reported that thirty percent of the planet's crust had been destroyed, but there was no change in life sign readings - the fleet determined that the Dominion had been using an automated transponder to broadcast false sensor readings, and the Founders had abandoned the planet. 150 Jem'Hadar attack ships, individually smaller and weaker than the larger ships, attacked and defeated the allied fleet with superior numbers and surprise.
The battle was an unmitigated debacle for the Tal'Shiar in losses of experienced personnel, and far worse for the Obsidian Order, which had not only been decimated, but caught with its own military hardware in violation of Cardassian law. The Order soon disbanded, and the Tal'Shiar would take years to rebuild.
The battle is cited by Trekkies as proof that the Romulans, Cardassians, and by extension the Federation, have the ability to destroy a planet. Warsies respond that the 30% figure was due to a similar cause as the false life-form readings, citing lack of visual evidence of destruction of such a large portion of the planet's surface and the fact that it was a Dominion trap. Other attempts to explain the discrepancy between the the reported 30% figure and the other facts of the episode include:
- they meant surface area, not volume
- they meant of the original target area and not the entire planet
However, even accepting the 30% figure at face value, the Death Star indisputably dwarfs the firepower of a fleet of any twenty ships, be they Romulan, Cardassian, or Imperial.