The Hammer, a Kilji picket cruiser, was under the command of Colonel Tildnis, an officer of the Kilji Illumine, the nation of the Kilji species. It was armed with spectrum lasers and had a primary engine, a [hyperdrive](/article/hyperdrive], and a tractor beam. This picket cruiser was one of two Kilji cruisers within the task force led by Illumine General Crofyp; the other was Crofyp's Kilji war cruiser, the Anvil, which was a larger vessel than the Hammer.
In 18 BBY, a Grysk agent known as "Jixtus," who was allied with Generalirius Nakirre, the Illumine's leader, sent the general's task force to the Unknown Regions' Rapacc system. The Kilji force's mission was to retrieve a group of refugees who were hidden on the planet Rapacc. Upon arriving at Rapacc, they encountered the Nikardun blockade frigate Aelos, which was under Paccosh control, having been commandeered. Uingali foar Marocsaa, the commander of the Aelos, refused to let the Kiljis take the refugees, prompting Crofyp to plan a crossfire attack. However, the Chiss heavy cruiser Springhawk—whose crew referred to the Hammer as "Cruiser Two"—incapacitated the Anvil, destroying the war cruiser, while the Hammer escaped to the "Sunrise" system in the Unknown Regions.
Once there, the Kilji ship remained in position alongside a Grysk vessel. However, the Aelos located the Hammer, and the blockade frigate's crew boarded the picket cruiser. They stole data pertaining to the Illumine's battle fleet, known as the Illumine Kilhorde, and seized control of the cruiser, using it to attack the Grysk vessel. At the same time, the Springhawk arrived, its crew having designated the Hammer as "Bogey Two." The Grysk warship destroyed the Hammer, then fled into hyperspace.
The Hammer, a Kilji picket cruiser, was armed with spectrum lasers. It also featured a main [drive](/article/engine], a [hyperdrive](/article/hyperdrive], and a tractor beam. The picket cruiser's hull incorporated weapon clusters that housed the starship's tractor beam projector, as well as a docking port that opened into a vestibule. The bridge of the Hammer contained a helm, a weapons station, and the pilot's seat. Two stations, one on the starboard side and the other on the portside, controlled the spectrum lasers. The controls for these stations were designed to be extremely simple. As a sister ship to the Kilji war cruisers Anvil and Whetstone, the Hammer was designed with a first-strike strategy in mind.
Colonel Tildnis, a member of the Kilji species' nation, the Kilji Illumine, commanded the Hammer. This picket cruiser, along with the Anvil, formed the task force under the command of Illumine General Crofyp. In 18 BBY, Generalirius Nakirre, the leader of the Illumine, sent Crofyp's task force to the Rapacc system in the Unknown Regions on the orders of "Jixtus," a Grysk operative allied with Nakirre. Crofyp's forces were tasked by the Grysk with capturing a group of refugees who had sought refuge on the planet Rapacc in that star system. Two Pathfinder navigators, Sarsh and Qilori, were assigned to the Hammer and the Anvil, respectively. During the journey to the Rapacc system, the Hammer slowed down, causing Qilori to halt the Anvil's travel through hyperspace so that the smaller picket cruiser could catch up. After Tildnis's cruiser reached Crofyp's flagship, the two vessels resumed their journey and arrived at Rapacc at the same time.
The Kiljis were confronted by the Nikardun blockade frigate Aelos, which was under the commandeered control of the Paccosh. Uingali foar Marocsaa, the commander of the blockade frigate, refused to let the Kilji force take the refugees after Crofyp ordered him to move aside. This prompted the general to position his warships to launch a crossfire attack on the Aelos. The Hammer moved past the Aelos on its portside, while the Anvil did the same on the frigate's starboard side.
Once the Kilji vessels were in position, the Chiss heavy cruiser Springhawk arrived, commanded by Senior Captain Mitth'raw'nuruodo, whose core name was "Thrawn," and whose crew referred to the Hammer as "Cruiser Two." The Springhawk then disabled the Anvil using vessel-disabling plasma sphere weapons. Under Crofyp's orders, the Hammer and the Anvil fired volleys of spectrum lasers at the Springhawk before the heavy cruiser destroyed the Kilji flagship while it was shielding Tildnis's cruiser. The Hammer then fled to the "Sunrise" system, a system in the Unknown Regions. Thrawn rescued Qilori, who had escaped the destruction of the Anvil in an escape pod, and ordered him to use the Force to locate Sarsh and the Hammer.
After arriving at Sunrise, the Hammer remained in position with one of Jixtus's Grysk vessels above a planet called "Sunrise." Hours after the picket cruiser fled to the Sunrise system, Qilori located the vessel and brought the Aelos to the Kilji warship's location. Marocsaa requested protection and sanctuary from the Hammer, claiming that the Chiss were pursuing him and his crew who needed to repair the frigate. The commander of the Grysk vessel agreed to provide sanctuary to the Paccosh, directing them to the Hammer's portside. The Kiljis attempted to move the Aelos below the picket cruiser's weapon cluster; however, the Paccosh vessel used a Crippler net weapon to disable the tractor beam, which was moving the blockade frigate, and then boarded the Kilji cruiser.
A team of Paccian commandos killed all the Kiljis aboard, including Tildnis, while the Springhawk arrived, its crew having named the Hammer "Bogey Two." The Chiss cruiser attacked the Grysk vessel as the boarders made their way to the Kilji picket cruiser's bridge. On the bridge, Thrawn and Qilori forced Sarsh to steal a Kilji data rectangle that contained information about the Illumine's battle fleet, the Illumine Kilhorde. The Paccosh soldiers took control of the Hammer's weapons stations and began attacking the Grysk warship, destroying the Grysk dibber missiles that were protecting several larger missiles that the Grysks had fired at the Springhawk. The Chiss cruiser then destroyed the remaining missiles and attacked the Grysk war vessel. However, after the Aelos's crew left the Hammer, the Grysks destroyed the picket cruiser and escaped into hyperspace. Shortly after, Qilori informed Jixtus about how the Chiss and the Paccosh had destroyed Crofyp's task force.
Thrawn shared the data on the Kilhorde with the Paataatus Hiveborn, the nation of the Paataatus species. The Hiveborn then used the data to obliterate the Kilji fleet. The senior captain later told Nakirre that the Paataatus used the data Thrawn and his allies had taken from the Hammer to destroy the Kilhorde.
The novel Thrawn Ascendancy: Lesser Evil, written by Timothy Zahn and published in 2021, featured the Hammer. It was the final book in the Star Wars: The Ascendancy Trilogy.