In the early days of the Clone Wars, CC-1004, along with ninety-nine other identical clone commanders, was pulled from his duties at the front and sent back to Kamino, where he was entered into a highly unorthodox, highly specialized training program designed to promote independence and outside-the-manual thinking among the Grand Army of the Republic's upper echelon.
Upon graduation of the program, CC-1004 adopted a new name, "Gree". The name stemmed from his new-found interest in the study of obscure alien species. The Gree were a relatively unknown species living outside the boundaries of the Republic. He reasoned that should anyone comment on his name upon hearing it, he would know he was talking with someone who shared in his intellectual pursuits. Gree's interest in alien species, however, was not limited to the vast databank libraries of Kamino.
As the war progressed, Gree's 41st Elite Legion saw itself become a division specializing in operations where cooperation with the locals was key. Time and again, the 41st Elite Legion found itself in grueling campaigns on primitive worlds.
As the Clone Wars reached its climax, Gree was paired with Jedi General Yoda and sent to the Wookiee world of Kashyyyk. Recognizing the severity of the mission, Gree took with him his two most distinguished divisions—Sarlacc Battalions A and B. Upon arriving on Kashyyyk aboard the Venator-class Star Destroyer Monitor, Gree had his men set up a hasty beachhead in order to prepare for the coming Separatist advance.
As the battle raged below him, Gree received an emergency protocol directly from Supreme Chancellor Palpatine himself. The iniative, officially known as Order 66, labeled all of the Jedi as enemies of the Republic. Gree moved to obey the order without question. However, as he raised his DC-15 towards the diminutive Jedi, Yoda's lightsaber found its way to Gree's neck before he could even fire a shot.