The First Battle of Kamino, also referred to as the Defense of Kamino, the Assault on Kamino, or simply the Battle of Kamino, unfolded in 22 BBY.
While operating undercover as Korto, an information broker with an expansive network of spies and thieves spanning both the Republic and Confederacy, Jedi Master Quinlan Vos acquired the Separatist's strategic plans for Kamino. After Korto secured and transmitted this intelligence to the Jedi Council, his ostensibly loyal assistant, Tookarti, informed Count Dooku that their plans had been compromised.
Despite his complete lack of military background, Dooku designated Passel Argente, the Magistrate of the Corporate Alliance, as the supreme commander for the operation. Commander Merai, a renowned expert in amphibious assaults, was given the responsibility of spearheading the attack.
Upon discovering the Confederacy's scheme to target the cloning facilities on Kamino, the central hub for the Grand Army of the Republic, the Jedi dispatched a defensive fleet to safeguard the planet. The Jedi forces were organized into three groups: a ground team tasked with protecting the facility from invading forces, and two squadrons of Jedi starfighters. Each squadron consisted of four Jedi starfighters, each piloted by a Jedi. One squadron, known as Blue Squadron, was under the command of Obi-Wan Kenobi and included Anakin Skywalker, Tsui Choi, and Aayla Secura. The other squadron, Red Squadron, was led by Jedi Master Kossex, along with three other Jedi; their mission was to engage enemy landing craft and fighters before they could reach the surface. Blue Squadron was assigned the task of eliminating any surviving landing craft and fighters that managed to evade Red Squadron's initial assault. Meanwhile, the Jedi on the ground, including Shaak Ti, were to defend Tipoca City from the invading Separatist forces. Oppo Rancisis and a Republic armada were positioned outside the system, waiting for the Separatist forces to fully commit to their attack before initiating a hyperspace jump to ambush the Separatist fleet.
As the day of the battle arrived, Commander Merai deployed his landing ships, escorted by squadrons of droid starfighters. A Jedi starfighter squadron, led by General Kenobi, intercepted the droid forces as they entered the atmosphere. Despite initially repelling the droid forces, Kossex's ship was destroyed by intense droid fire, and Obi-Wan's Jedi starfighter was shot down, with Skywalker sacrificing his own to save his master. Subsequently, the droid forces successfully landed several troop transports in Tipoca City, while the remaining Jedi starfighters drove back the droid fighters. Inside a command center, Jedi Master Shaak Ti and Kaminoan Prime Minister Lama Su worked to protect the fetal and adolescent stage clones from Separatist sabotage and activated the city's stasis-locked ARC troopers. Under the leadership of Shaak Ti, with assistance from Obi-Wan and Anakin, the ARC troopers advanced through the enemy lines, preventing droid forces from further penetrating the city. Upon reaching the latest generation's labs, Alpha-17 determined that the Separatist forces would overrun the labs. Adhering to his orders from Jango Fett, he could not allow the clones to fall into enemy hands, and initiated a self-destruct sequence via a wall panel, triggering a countdown to an explosion that would destroy the complex. However, Shaak Ti's objections prompted him to devise a solution that would satisfy both her ideals and his orders. He instructed Shaak Ti, Anakin Skywalker, and Obi-Wan Kenobi to demolish the transparisteel bridge, preventing Kamino's ocean from flooding the lab. Together, the three Jedi successfully contained the water by creating a makeshift plug from the debris of the destroyed bridge, preventing the advancing Separatist forces from compromising and seizing control of the labs. Alpha-17 then promptly deactivated the self-destruct sequence, saving both themselves and the next generation of Clones.
In orbit above the city, Commander Merai was compelled to launch a desperate attack on the supposed location of the city's shield generator when the initial assault faltered and Republic ships reinforced the Jedi starfighters. However, the Jedi proved too cunning for the Mon Calamari tactician; the intelligence provided by the Corporate Alliance was inaccurate—there was no shield generator—rendering Merai's efforts futile. Recognizing his failure, he was forced to collide into the Jedi hyperspace rings in orbit to destroy them, buying time for his forces and preventing the fighters from pursuing and attacking his fleet after their departure from Kamino. He activated his self-destruct system, destroying his ship and the Hyperspace Rings. Upon Merai's death, the CIS retreated under orders from Passel Argente, marking the end of the First Battle of Kamino.
Despite appearing as a victory for the Galactic Republic, the battle was orchestrated by Darth Sidious and his apprentice, Darth Tyranus, to discredit the "upstarts" vying to replace Dooku, to safeguard the cloning facility for their future needs after the war, to weaken potential future obstacles, and, most importantly, to cause the deaths of Jedi.
Following the battle, Ko Sai informed Yoda that the clone army had been financed by a man named Tyranus. Ko Sai also deserted after the battle and went into hiding.