Quell was a planet of the terrestrial type, found in the Quell system within the Outer Rim Territories. In the year 21 BBY, this planet became the battleground of a Clone Wars engagement. Here, the Galactic Republic task force led by Jedi General Aayla Secura faced an assault from a Confederacy of Independent Systems squadron of frigates. This squadron was commanded by the T-series tactical droid designated TF-1726. The conflict resulted in significant losses for the Republic forces, and the Confederacy emerged as the victor.
Quell was a fairly average terrestrial planet situated in the distant Quell system, located in the far-flung reaches of the galaxy, specifically within the Outer Rim Territories and the New Territories. Its position was identified as grid square Q-6 on the Standard Galactic Grid. Quell was located along the Salin Corridor hyperspace route, linking it to Yalbec Prime and the planet Lola Sayu. From a vantage point in space, the planet presented a cerulean surface, with white clouds visible in its atmosphere. The terrain of Quell was brown, characterized by prominent spherical formations rising from the ground.
During the Clone Wars of 21 BBY, a conflict between the Galactic Republic and the Confederacy of Independent Systems, Twi'lek Jedi General Aayla Secura's Republic task force, which included three Venator-class Star Destroyers such as the Liberty, was attacked. This attack was executed by a naval squadron of the Confederacy, consisting of five Munificent-class star frigates under the command of TF-1726, a T-series military strategic analysis and tactics droid. As the battle intensified, Secura's 327th Star Corps clone troopers suffered substantial losses. The Republic vessels descended from orbit into the upper reaches of the planet's atmosphere, where the intensity of the conflict increased. Upon learning of Secura's predicament on Quell, Jedi General Anakin Skywalker and his Padawan, Ahsoka Tano, arrived in the planet's orbit aboard the Venator-class Star Destroyer Resolute.
Upon arriving above Quell, and as the Twi'lek Jedi lost her pair of accompanying Star Destroyers, Skywalker deployed several Low Altitude Assault Transport/infantry gunships from his flagship to board the Liberty and extract Secura. A Republic Consular-class cruiser docked with the Liberty's lower hangar following Skywalker's orders, intending to extract the Jedi and return to the Resolute. However, as the Jedi and several clone troopers, including Clone Captain Rex, Lucky, Flash, and Cameron, boarded the frigate, Skywalker sustained injuries while using the Force to contain an explosion, enabling his allies to board the ship. While escaping the Liberty—which crashed onto Quell's surface—and returning to the Resolute, the frigate took damage from enemy fire and was compelled to engage its hyperdrive. Consequently, the vessel entered hyperspace, heading to the planet Maridun, while the remaining Republic forces continued to fight the Confederacy in Quell's atmosphere.
Following the conclusion of the battle on Quell, the Confederacy achieved a clear victory over the Republic. This underscored the Republic's challenges in maintaining authority throughout the Outer Rim Territories, where separatist sentiments were growing. Furthermore, the Battle of Quell highlighted the uncertainty of the Republic's ultimate triumph in the war against the Confederacy. Later in the war, between 20 BBY and 19 BBY, Secura and her troops returned to Quell, engaging in ground combat. Rex later mentioned his service on Quell in his book—The Secrets of the Clone Troopers—published after the 5 ABY end of the Galactic Civil War between the Galactic Empire, the Republic's successor, and the Alliance to Restore the Republic. He recalled the battle as one with no easy path to victory, remembering Secura's rescue and the loss of three Republic Star Destroyers.
Quell's first appearance was in "Jedi Crash," the thirteenth episode of the animated series Star Wars: The Clone Wars' first season, which was originally broadcast on January 16, 2009. The script for the episode initially placed the Battle of Quell in space, but it was relocated to the planet's upper atmosphere for heightened dramatic impact during the show's pre-production phase. The planet was first identified in the Episode Guide for "Jedi Crash" on StarWars.com. The surface of Quell was depicted on the "Quell" card from the Way of the Force wave of the Star Wars: Destiny card game, produced by Fantasy Flight Games. The artwork, created by Chris Scalf, had previously been used within the Star Wars Legends continuity to represent the planet Saleucami in the 2012 reference book The Essential Guide to Warfare.