WARNING: The following contains spoilers for Star Wars: The Clone Wars Season 7, streaming now on Disney+
Star Wars: The Clone Wars has become a high point in the franchise, and has introduced some fantastic and beloved new characters to the Star Wars galaxy. One of the show's breakout characters is clone trooper, Captain Rex. He served in the 501st as one of Anakin Skywalker's most trusted soldiers and closest confidant.
The follow-up series Rebels establishes that Rex survived the wars, but there has been a lingering hole in his narrative: Why didn't he appear in Revenge of the Sith? In The Clones Wars' latest episode, "Old Friends Not Forgotten," viewers finally get an answer.
His absence from the film is due to his friendship with another Clone Wars favorite, Ahsoka Tano. The two had developed a close bond over the course of the war, with Rex mentoring the young Jedi while respecting her authority. After being absent from Season 6 following her expulsion from the Jedi Order, Ahsoka is back, finally reuniting with her former master, Anakin Skywalker. Ahsoka contacted Anakin to ask for the Republic's help on behalf of Bo-Katan Kryze of the Mandalorians.
While debating what to do, Obi-Wan and Anakin are called back to Coruscant on an emergency mission. Coruscant is under attack by General Grievous and Chancellor Palpatine is at risk. Fans of the films know that the attack they are on their way to is the opening scene of Revenge of the Sith, meaning that Anakin and Obi-Wan won't be able to help, and thus the show has finally caught up to the films.
Not wanting to betray Ahsoka's trust, Anakin offers to send half of his 501st Legion to help the Mandalorians against Maul. He promotes Rex to Commander, assigns him to lead these troops and suggests Ahsoka serve in an advisory capacity. The clock is ticking to save Palpatine, so Obi-Wan agrees to Anakin's plan. Rex and Anakin share a rushed goodbye, not knowing it will be their last.
After years of speculation, fans finally have an answer as to why Rex wasn't there for the films because he's helping Ahsoka during the Siege of Mandalore. His absence has become a particular wrinkle with fans, especially after his re-appearance in the follow-up series, Rebels. Depicted as an old man due to the clone's accelerated aging, it's explained he removed his control chip before Order 66 was enacted and went to live in seclusion.
How and when he removed his chip has yet to be answered. He is aware of the chip's existence and the potentially sinister purpose behind it, but his Clone Wars appearance doesn't yet have the scar on his head that he has in Rebels from the chip's removal. There are still holes in Rex's story, but with three episodes left in The Clone Wars final season and the show now running concurrently with the films, there is still a chance for more answers.
Streaming on Disney+, the final season of Star Wars: The Clone Wars stars Matt Lanter as Anakin Skywalker, Ashley Eckstein as Ahsoka Tano, Dee Bradley Baker as Captain Rex and the clone troopers, James Arnold Taylor as Obi-Wan Kenobi, Katee Sackhoff as Bo-Katan and Sam Witwer as Maul. A new episode arrives each Friday.