The clone who took the name "Rex" was grown on Kamino like his fellow clone troopers, bred to be among the best soldiers in the galaxy. Rex received additional command training and earned the rank of captain, overseeing Torrent Company within the 501st Battalion. The Republic's clone army saw its first action against Count Dooku's Separatists during the Battle of Geonosis. Rex and his troopers fought well, earning veteran status within the clone army.

Soon after Geonosis came the Battle of Christophsis, in which Anakin Skywalker and Obi-Wan Kenobi led Rex's unit against the droid forces of General Loathsom. Rex held the line against Loathsom's droids so Skywalker and his new Padawan Ahsoka Tano could take out the enemy's shield generator. With his superior officer Commander Cody, Rex also helped uncover a traitor within the clone ranks.

The triumph on Christophsis gave Rex little time to rest. He and his men immediately accompanied General Skywalker to Teth, where they assaulted a mountaintop monastery containing Jabba the Hutt's kidnapped nephew, Rotta. Using their AT-TE walkers, Rex and his clones scaled the vertical cliff side and fought their way inside. The arrival of dark side assassin Asajj Ventress complicated things, but Rex kept fighting until the Jedi made it offworld with the young Huttlet.

Rex and Commander Cody arrived to inspect a unit of rookie clone troopers at a listening post on the Rishi moon. Separatist droid commandos had already taken over, and Rex and Cody teamed up with the rookies to regain control of the facility. Rex inducted the survivors into the 501st Battalion.

General Grievous planned to strike at the planet Bothawui, but the Republic arranged an ambush for the enemy armada. Rex and other clones placed AT-TEs on the drifting rocks of a planetary ring, and fired on the Separatist flagship when Grievous least expected it.

After the victory at Bothawui, a follow-up mission required the Republic to destroy the Separatist outpost at Skytop Station. Rex accompanied Anakin and Ahsoka inside the station to plant explosive charges. General Grievous nearly killed Rex, but Ahsoka distracted the Separatist cyborg. The group survived Skytop and escaped as the station sank into the lower atmosphere.

An urgent call from Quell put Captain Rex into action to rescue Jedi General Aayla Secura from a Separatist rocket droid attack. Rex and Ahsoka hooked up with Secura and Commander Bly and then escaped in a frigate.

However, their blind hyperspace jump ended in a crash landing on Maridun. With Anakin injured and out of commission, Rex watched over the campsite while Commander Bly, Ahsoka, and Aayla searched for help. Rex barely survived a close encounter with a hungry mastiff phalone before members of the local Lurmen colony arrived to lend a hand.

The Separatists arrived on Maridun soon after. Led by General Lok Durd, they intended to use the planet as a testing ground for their defoliator -- a new weapon that would exterminate all life inside its radius but leave battle droids unharmed. Captain Rex and Commander Bly helped the Lurmen defend their village, while Anakin Skywalker destroyed the enemy's weapon.

On the frozen world of Ord Plutonia, Captain Rex agreed to protect the Pantoran chairman Chi Cho from the local Talz tribes. Tensions between the Pantoran delegation and the Talz soon exploded. Though Rex did his best to hold off the enemy raiders, the chairman died from his injuries. His successor, Senator Riyo Chuchi, wisely listened to the Talz and hammered out a peace agreement.

To halt an outbreak of the notorious Blue Shadow Virus, Rex participated in an assault on an underground research laboratory on Naboo. Rex and his troopers rescued Padmé Amidala and Jar Jar Binks from Dr. Nuvo Vindi, but accidentally exposed themselves to the deadly virus. Fortunately, Anakin and Obi-Wan tracked down an antidote and restored Rex to fighting shape.

On a mission to stop the bounty hunter Cad Bane who had absconded with a Jedi holocron, Anakin Skywalker exercised his trademark improvisation. Skywalker ordered Rex to take a pressurized AT-TE and use it as a boarding craft to land aboard Bane's retreating frigate.

The crater left by an electro-proton bomb on Malastare triggered a sinkhole that awakened a hibernating Zillo Beast. Rex served with the unit that subdued the animal, and later helped contain its rampage after it was transported to Coruscant.

On Geonosis, Poggle the Lesser regained control of his homeworld on behalf of the Separatists. The Republic launched a campaign to retake the planet, and Captain Rex saw action on the front lines. Thanks to the efforts of Ahsoka Tano and Barriss Offee, Poggle's droid factory exploded and the Republic wiped out the Geonosian resistance.

Rex led a squad to search for General Grievous in the swamps of Saleucami. Droid snipers gravely wounded Rex, and while his troopers searched for medical attention they ran into ex-trooper Cut Lawquane. Rex had little respect for Cut at first, who had abandoned his fellow clones after the first Battle of Geonosis to live a quiet life as a farmer. But Cut fought bravely when Separatist droids attacked, winning Rex's grudging admiration.

Aboard the star yacht Coronet, Rex defended Mandalore's Duchess Satine Kryze from killer droids dispatched on behalf of the Mandalorian Death Watch.

The Separatists launched a bold attack against the cloning hatcheries of Kamino. To the clones like Rex, this was an assault on their home. Rex and Cody fought proudly to repel the droid invaders, eventually rallying clone cadets to help turn the tide of the battle and secure Kamino for the Republic.

When Jedi Master Even Piell and Republic captain Tarkin became captives in the impregnable Separatist prison known as the Citadel, Rex joined Anakin, Obi-Wan, Ahsoka, and Cody to break into the facility. Rex and the others outwitted the Citadel's life-detecting sensors by freezing themselves in carbonite. The Citadel mission proved to be one of the most difficult undertaken by Rex since the start of the Clone Wars.

One of the most grueling campaigns of the Clone Wars was the fight for Umbara, a shadowy world where the clones had to contend with fearsome predators and Umbaran militia armed with high-tech starfighters and ground vehicles.

The 501st’s fortunes changed when Anakin Skywalker was ordered to return to Coruscant and Pong Krell took over command. Krell treated the clones as if they were droids and not living beings, pushing them past the point of exhaustion and sacrificing their lives in wasteful frontal assaults. In issuing orders he addressed Rex as CT-7527, ignoring the name the captain preferred.

Rex disliked Krell’s command style and objected to his brute-force tactics. But while other veteran clones in the 501st openly groused about Krell, Rex supported his Jedi General. He had been trained since birth to follow orders, even ones he disagreed with.

The 501st took many losses as it followed Krell’s plan, but the clones’ advance stalled near a strategically important Umbaran airbase. There, Rex infuriated Krell by sending two of his troopers – Fives and Hardcase – to infiltrate the airbase and steal a pair of Umbaran fighters. The fighters gave the clones badly needed air support, allowing them to take the airbase.

Krell decided to continue a Republic drive on the Umbaran capital, ignoring the certainty of more clone casualties from missile fire. The prospect of another suicide mission left the 501st on the brink of open rebellion. Fives proposed using the Umbaran fighters to disrupt the Separatist supply chain, a plan Krell rejected. Fives decided to go ahead with the plan anyway, insisting to Rex that he wouldn’t follow orders that were plainly wrong.

Rex warned Fives he couldn’t cover for him if he disobeyed orders, but then lied to Krell, claiming the fighter launch was an authorized recon mission. Fives’ plan succeeded, but Krell ordered him and clone trooper Jesse court-martialed and executed.

The clones refused to execute Fives and Jesse, and Rex ordered them freed. Krell then ordered Rex’s troops to intercept Umbarans disguised in clone armor. That was a lie, as an anguished Rex discovered: Krell had told the two clone forces the same story about disguised Umbarans and sent them into battle against each other.

Rex and his platoon decided to arrest Krell as a traitor, capturing the Jedi after a pitched battle and executing him rather than let him fall into the hands of the Separatists he’d aided. The Republic captured Umbara, but Rex was left with disquieting questions about the war and how it was being conducted.

Rex shed his clone armor for a slaver’s garb when he joined Obi-Wan, Anakin and Ahsoka in infiltrating Zygerria in an effort to rescue the enslaved colonists of Kiros. Rex and Obi-Wan were taken captive and treated brutally in slave pits on the planet Kadavo. When they got a chance to fight back Rex didn’t hesitate, killing the merciless Keeper Agruss with a hurled electro-staff.

With war raging across the galaxy, Anakin Skywalker suggested training rebels as insurgents on Separatist-held planets. Rex joined him, Ahsoka and Obi-Wan on a mission to Onderon to test the idea. After making contact with the rebels, Rex showed them techniques for fighting foes ranging from battle droids to AATs.

After Ahsoka Tano was imprisoned for the murder of saboteur Letta Turmond, Rex had to confront evidence indicating the Padawan he had served with had killed other clones. Rex couldn’t believe Ahsoka would do such a thing, but obeyed the order to find Ahsoka in Coruscant’s lawless underlevels and apprehend her.

After clone trooper Tup killed Jedi General Tiplar during the Battle of Ringo Vinda, Rex helped interrogate the clone. Rex then allowed ARC trooper Fives to accompany him and Tup to Kamino, where the Republic hoped medical tests would reveal what happened to him.

When Rex saw Fives again, the ARC trooper had apparently gone mad, attacking Supreme Chancellor Palpatine and summoning Rex and Anakin to listen to his story. What he said sounded insane: Every clone had been implanted with a bio-chip to ensure they follow orders, and the Kaminoans and the Jedi were part of the conspiracy to cover up the secret.

Clones led by Commander Fox burst in to arrest Fives. The ARC trooper grabbed one of Rex’s pistols and was felled by blaster fire. He died in Rex’s arms, using his last breath to warn his old comrade that the conspiracy was bigger than anyone could imagine.

Years after Rex fought in the Clone Wars, he retired with fellow clones Wolffe and Gregor. The trio spent their days traveling the planet Seelos in a modified AT-TE, telling stories and slinging for joopa until the day they were confronted by former Jedi Kanan Jarrus and the Ghost crew.

Initially hesitant, Rex was puzzled when Ezra stated the numbers “7567,” his birth number. At the revelation of his identity as a clone, Kanan ignited his lightsaber in defense, ready to take down the clones that he hadn’t seen since they tragically killed his master during Order 66.

Woffe and Gregor in turn pointed their blasters at Kanan to defend themselves against the Jedi that betrayed them. Rex coaxes his friends to put down their weapons and remember that Kanan was not one of the Jedi that turned on them. Ezra gains the trust of the clones when he explains that his group was sent to Rex by his former commander, Ahsoka Tano.

Ezra explains to Rex that Ahsoka is in need of their help to fight the Empire but Rex claims that they retired from battle when the Republic was toppled. Aside from their help as soldiers, Ezra barters for their help locating a safe location for a base along the Outer Rim.

While listening to Kanan retell the events of Order 66 to Ezra, Rex reveals to the two that he and his fellow retired soldiers removed their control chips prior to the killings of the Jedi. He was never involved in the betrayal that Kanan holds against him.

Rex goes along with Gregor’s plan to use Zeb as bait to catch the enormous joopa below the ground of Seelos and fires the shot killing the beast and releasing Zeb. He keeps up his end of the bargain by providing Sabine with a list of coordinates for safe base locations. Rex compliments Ezra on his bravery and Ezra asks him again to join the crew but he declines, claiming he has out-served his purpose for combat. The Clone Wars made him question the purpose of the lives lost in battle.

The conversation was quickly interrupted when Sabine discovered the clones warned the Empire of their arrival on Seelos. Rex discovers it was Wolffe who contacted the Empire in order to protect his squad. He clears up to Wolffe that they are no longer fighting a war and they cannot live in fear of the Empire for the rest of their lives. To make up for Wolffe’s mistake, the former captain shoots the probe droid that has been tracking the rebels but it is too late.