Star Trek: 10 Things We Now Know About The Breen
8. See How They Run
The Star Trek: Deep Space Nine episode By Inferno's Light taught us a valuable life lesson: "Never turn your back on a Breen." (Very xenophobic, if you ask me!) The Romulans, and especially those jailor Jem'Hadar, had to learn that the hard way. During their Second Empire, the Klingons had also lost an entire fleet sent to conquer the Breen homeworld, as Worf reported in Til Death Do Us Part. Despite the axiom, soon the Federation and all its allies would be running from the Breen when the species became a formidable late-stage belligerent in the Dominion War.
News is always the most chilling when it must be delivered matter-of-factly. "We just received a priority-one transmission from Starfleet Command. The Breen have attacked Earth," is how Colonel Kira relayed that particular piece of devastating information over the comm to Captain Sisko. The strike was a distinctly ballsy opening salvo on the part of the Breen, leaving Starfleet HQ (and the Golden Gate Bridge) a smouldering wreck. Had the Klingons not been on friendly terms at the time, they just might have been green with envy!
The Breen followed that up with a counteroffensive against the Federation-held Chin'toka system. Sent to join the fight, things finished in disaster for the Defiant and the, in total, 311 Federation, Romulan, and Klingon ships at the end of the Breen energy dissipator weapon. The target vessels were almost instantly drained of power (except one — the Ki'tang), leaving their occupants either dead or fleeing for their lives in escape pods.
The Breen 'interceptor' vessel used in that battle (and several more) was designed by the legendary John Eaves. His early sketch of the ship for the episode Penumbra is shown in the Star Trek: Deep Space Nine Companion and "hints at the asymmetrical shape the producers wanted". From Tuvok in Scorpion, we got a hint at how Breen vessels work — they are "organic-based". Prior to that, in Hero Worship, Data had also suggested that the Breen have cloaking technology.
If 24th century Breen ships weren't impressive enough for you, then behold the beast that is the Breen dreadnought, the mightiest, most massive vessel in the 32nd century Breen fleet! It loomed large and menacingly over Federation HQ in Erigah. We've not yet seen it in a fight, but it has been confirmed that this is the same ship that destroyed Fed HQ in Face The Strange, and what initially appeared to be a space station in Mirrors.