Hammer wore white ARC trooper armor that featured red and gray highlights, a kama, and two pauldrons. As part of their equipment, the trooper wielded either two DC-17 hand blasters or a DC-15A blaster rifle. As a clone of Jango Fett, the trooper stood at 1.83 meters. Additionally, Hammer had received further training due to their ARC status.
Hammer oversees Domino Squad in training from above.
Grown on the planet Kamino from the DNA of Jango Fett, a bounty hunter who became the template of the clone trooper army, the clone named Hammer was an Advanced Recon Commando, or ARC trooper, in the Grand Army of the Republic after being trained in the ARC program. Hammer participated as a Clone ARC Commander in the pan-galactic Clone Wars between the Galactic Republic and the Separatist Alliance, serving in the Republic's Rancor Battalion alongside ARC Commanders Colt, Havoc, and Blitz.
Early during the Clone Wars, in 22 BBY, the battalion was stationed on Kamino alongside Colt, Havoc, and Blitz, who oversaw the training of clone cadets. Hammer walked with two other clone troopers in a hangar at Tipoca City where Domino Squad, Bravo Squad, and two other cadet units were present, and the commando listened to speeches given by Master Chief Bric and Commander Colt.
Hammer was later present above the arena housing the Citadel Challenge training course, observing the cadets' final exam. Alongside several other clone cadets, the group witnessed Domino Squad fail to complete the challenge. However, after Jedi General Shaak Ti allowed the squad to try the final examination a second time, the Hammer saw the group succeed at the test.
Later in the war, during 21 BBY, the Separatist Alliance launched an attack on Kamino. During the naval engagement, Separatist Munificent-class star frigates launched Trident-class assault ships disguised as debris into the oceans below. The assault ships then attacked the Tipoca City Military Complex, causing the city's forces to ready for battle. As such, the Hammer joined Commanders Colt, Havoc, and Blitz at the main hangar to defend it and direct Republic forces. As Havoc gave an assignment to troopers Echo and Fives, Hammer was directing a number of other troops.
Hammer participated in the Battle of Kamino, defending the main hangar alongside Jedi General Shaak Ti.
When a Trident-class assault ship prepared to breach the hangar, Hammer gave a hand signal to a clone armed with a Z-6 rotary blaster cannon, directing them to hold fire. After the hangar was breached by a second assault ship, Republic troops engaged the AQ-series battle droids that had deployed from the enemy craft, Hammer continued to command Republic forces. Eventually, Separatist forces grew thin and were pushed back to the main hangar. With the deaths of Colt and Havoc, Hammer remained in the hangar and was joined by Shaak Ti.
Hammer and other clone troopers subsequently managed to destroy both Trident-class assault ships that had breached the main hangar, while Commander Blitz directed a trio of Advanced Recon Force Scout Troopers, ordering one to fire on an assault ship with a rocket launcher. After the Separatist forces were ultimately defeated, Hammer was near Clone Marshal Commander Cody and Clone Captain Rex as the pair promoted Echo and Fives to ARC trooper status.
Hammer had received ARC training at one point prior to serving as an ARC trooper, and achieved the rank of Clone Arc Commander. During the Battle of Kamino, the ARC trooper fought on the front lines, commanding other troopers and engaging Separatist forces.
At birth, like the other clone troopers, Hammer was implanted by the Kaminoan scientists with a behavioral modification biochip to ensure that the trooper would not resist certain orders. As an ARC trooper, Hammer made use of white Phase I ARC Trooper Armor with red markings, which included a helmet with a rangefinder; a kama; a double pauldron; additional gray armor plating on the chest, arms, and legs; a survival pack; and two holsters for DC-17 hand blasters. Additionally, Hammer was armed with a DC-15A blaster rifle.
The Advanced Recon Commando first appeared, albeit unnamed, in the episode "Clone Cadets," the first episode of the third season of the animated television series Star Wars: The Clone Wars. The episode aired on September 17, 2010. Although not established in any official source, Lucasfilm Story Group executive and Keeper of the Holocron database Leland Chee mentioned on Twitter in 2021 that the commando was named "Hammer" during the episode's production. Two digital cards released through the Star Wars: Card Trader game, the first released on October 12, 2018 and the second on February 21, 2019, used images of Clone ARC Commander Colt but referred to Colt as "Clone ARC Commander Hammer."