Hammerly was a human female who served as a chief sensor officer of the Imperial Navy in the years before the Galactic Civil War. She served under Commander Thrawn aboard the starship Thunder Wasp during the mission to Umbara as a Senior Lieutenant. Following the Cyphar Incident, Hammerly stalled Thrawn's superiors, who were furious due to his actions in the event. Hammerly was eventually promoted to the rank of commander and served under Thrawn, now a commodore, for a second time aboard the Imperial I-class Star Destroyer Chimaera. She participated in battles against the Grysks and in a skirmish against the Third Fleet.
Due to Hera Syndulla's failed attack against the Lothal factory and the theft of the Defender Elite, Grand Moff Tarkin called the Chimaera to discuss the funding for Thrawn's TIE/D Defender program with Emperor Palpatine. Thrawn asked Commander Hammerly to have Governor Arihnda Pryce informed about his immediate departure to Coruscant. En route to the meeting on Coruscant, Hammerly informed Thrawn that Chimaera received a new set of coordinates from Tarkin to rendezvous with him in the Sev Tok system aboard the ISD Firedrake, the flagship of the Empire's Third Fleet led by Grand Admiral Balanhai Savit.
Due to Hera Syndulla's failed attack against the Lothal factory and the theft of the Defender Elite, Grand Moff Tarkin called the Chimaera to discuss the funding for Thrawn's TIE/D Defender program with Emperor Palpatine. Thrawn asked Commander Hammerly to have Governor Arihnda Pryce informed about his immediate departure to Coruscant. En route to the meeting on Coruscant, Hammerly informed Thrawn that Chimaera received a new set of coordinates from Tarkin to rendezvous with him in the Sev Tok system aboard the ISD Firedrake, the flagship of the Empire's Third Fleet led by Grand Admiral Balanhai Savit.