Historically, the Klingons were among the first to discover the consequences of underestimating the Breen. As revealed in "'Til Death Do Us Part", during the Klingon Second Empire, Chancellor Mow'ga ordered an entire fleet of Klingon warships to invade and conquer the Breen homeworld. The fleet never returned and was never heard from again. The Romulans have a saying: "Never turn your back on a Breen". This adage was first stated (and illustrated) in the 1997 fifth season "Deep Space Nine" episode "By Inferno's Light", in which a captive Breen grabbed a disruptor pistol from the holster of a Dominion guard, whose back was turned to him in a Dominion asteroid prison, and used it to disintegrate two Dominion guards at the same time as one of them killed the captive. The Breen in question had not done anything besides sit quietly up until that point, giving no indication that he would be a threat.