R7-A7, nicknamed Arseven, was the personal astromech of Jedi Padawan Ahsoka Tano during the Clone Wars. This unit participated in the Battle of Ryloth assisting Ahsoka to defeat the Separatist blockade.
- "I don't know. I don't know why the clones are doing this, but we might be able to do something about it."
- ―Ahsoka Tano to R7 and the droids after Order 66 is issued
Late in the war, renegade Sith Lord Darth Maul was located on Mandalore by R7's former master, Ahsoka Tano. With the aid of the Mandalorian Nite Owls, Tano led a Republic invasion force to lay siege to the planet and successfully captured Maul. Tano then accompanied Clone Commander Rex to escort Maul back to Coruscant for trial by the Jedi Council.
R7 was present aboard the Venator-class Star Destroyer transporting Maul, powered down in a recharge station for the voyage. However, Supreme Chancellor Palpatine contacted the ship and ordered Commander Rex to execute Order 66, the contingency directive that marked all Jedi for termination as traitors to the Galactic Republic. Still viewing Ahsoka as a Jedi, the Clone Troopers turned on their former commander and attempted to kill her.
While fleeing her pursuers, Ahsoka found R7 and powered him up for his help. R7, along with two other droids, G-G and CH-33P, warned her of the danger and inquired what was happening. Ahsoka didn't know why the clones betrayed her, but had a lead given to her by Rex just before he attacked. All three droids eagerly volunteered to help Ahsoka. She told R7 to access the ship's central computer for secure files on CT-5555, the rogue clone who investigated the inhibitor chips implanted in all Clone Troopers. His findings, although covered up by the Kaminoans, revealed to Ahsoka that the inhibitor chips forced the clones to kill their Jedi leaders against their will.
R7 then helped Ahsoka capture Rex by sealing off all doors in a hallway, separating him from his men. R7 projected a holographic message of Ahsoka to him, explaining that she knew the clones had no choice in following this order. Still under the control chip's influence, Rex demanded R7 to tell him where she was. When Ahsoka appeared behind him, Rex turned to shoot but was stunned by the droids, who then helped her bring him to the medbay.
R7 initiated a medical scan of Rex's brain to locate the chip and remove it. Ahsoka connected with Rex using a Force technique that calmed his mind, enabling R7 to locate the chip. As Clone Troopers attempted to break into the medbay, Ahsoka had R7 surgically remove the chip from Rex's brain, neither of them certain if it would work. But once Rex emerged from the procedure, he helped Ahsoka fight back the clones and apologized for his actions.