These two unnamed Klingon Birds of Prey help Duras ship by launching a third attack on the Enterprise NX-01, captained by Jonathan Archer, which was preparing to go into the Delphic Expanse in 2153. This time, Enterprise managed to evade the attack by entering the Expanse, something which Duras was willing to risk, but the other ship captains were not. The two Klingon Birds of Prey reluctantly withdraw while Duras continued his attack on the Enterprise. It is unknown where these two ships went. It is probably likely they went back to Klingon territory. (ENT: "The Expanse")
This Bird-of-Prey was seen in the "mirror" title sequence for the two part "In a Mirror, Darkly". Footage of Enterprise attacking Duras' Bird-of-Prey in ENT: "The Expanse" was used to depict this attack.