CT-21-0408, nicknamed "Echo," as he was known for "echoing" the standard rules and procedures established for clones, was a clone trooper who served in the Grand Army of the Republic during theClone Wars. Early in his career, Echo lived within Tipoca City, thecapital city of the planet Kamino, and trained in its military complex. As a clone cadet, Echo was part of the squad Domino Squad, overseen by the Siniteen bounty hunter Bric. Echo stayed with Domino Squad until the unit passed their final test; the completion of the test allowed the members of Domino Squad to become battle-ready clone troopers. For his first off-world assignment, Echo stood guard at Rishi Station, a listening post located on the moon of Rishi, where he and other rookie clone troopers were stationed. When theConfederate General Grievous implemented an attack on the Rishi Station to capture it before proceeding to Kamino. His plan, however, was thwarted by Echo, fellow troopers Fives, Hevy, and clone officersCody and Rex. Echo, along with Fives, were rewarded with medals for their service on the Rishi moon and were inducted into the 501st Legion.



Skywalker, having contacted R2 to land the shuttle near their location, led his group through the tunnels. When they reached a dead-end, they were ambushed by several commando droids, which were armed with energy shields. Without warning, Tano tossed a few thermal detonators under the droids' feet, which destroyed them. After Tano used more explosives to blow their way through the rock, Echo and the others proceeded toward a nearby pipeline. Using the pipeline as a way to find an escape route that would lead them toward their landed shuttle, Echo and the team soon reached an exit point of the pipeline. However, outside of the exit hatch, a battalion of battle and crab droids ambushed them. The group escaped, and Skywalker tossed a grenade into the fuel line, and the resulting explosion destroyed the droids. Skywalker's team went to Kenobi's position, finding the Jedi Master and his men pinned down by droids that were guarding the shuttle. Echo and Fives joined the battle, as more and more droids arrived.^[3]


When a commando droid, who was stationed on top of a watch tower, began to fire at their shuttle with a laser cannon, Echo reported this to Skywalker. Skywalker and Piell swooped in to attack on a commandeered STAP, but were knocked out. Determined to protect the shuttle, Echo picked up a fallen commando droid's shield to defend himself, and attempted to reach the shuttle. However, the droid destroyed the Republic team's shuttle,^[3]killing Echo in the process.^[4] Despite this, the Republic strike team was successfully evacuated by Masters Koon, Adi Gallia, and Saesee Tiin, who were leading a Republic fleet. However, Piell died before the rescue forces arrived, but he passed his knowledge of the Nexus Route to Tano.^[14]