Manx was a Klingon Defense Force officer who served as the second-degree tactical officer on the IKS Gothspar. His superior and rival was then-Lieutenant Martok. He approached Martok with evidence of Kultan's dishonor involving bioweapons, expecting Martok to confront Kultan and die in combat, allowing Manx to take Martok's role as main tactical officer.
Unfortunately for Manx, Martok reacted differently, confronting Gothmara, his lover (and the producer of the bioweapons), setting off a chain of events that destroyed the Gothspar. (DS9 - The Left Hand of Destiny novel: Book Two)