The Second Battle of Rhen Var was an early conflict during the Clone Wars. Although still a minor planet in terms of overall strategic importance to the Republic, Rhen Var held the ruins of the temple which held the tomb of fallen Jedi Ulic Qel-Droma and contained information that was vital to the destruction of the Dark Reaper.
After the Confederacy of Independent Systems' overwhelming victory that had secured their hold of Rhen Var in the days prior, Jedi Knight and General, Obi-Wan Kenobi and his Padawan, Anakin Skywalker launched an assault to retake the planet. During the landing, an Acclamator-class assault ship carrying the experimental AT-XT walkers was shot down, crashing in a wide, snow-covered canyon that quickly came under attack from Separatist forces determined to ensure nothing could be salvaged. Kenobi and Skywalker gathered their forces and moved with haste toward the crash site in Saber-class fighter tanks, joining up with the already operational AT-XTs in defending the downed transport, buying time for the surviving walkers to mobilize and escape the wreckage. When the area around the transport was secure, Skywalker took command of a squadron of the bipedal walkers from the cockpit of an AT-XT himself and moved on the enemy's fueling station. The walkers were equipped with powerful mortar cannons and after several volleys, the depot was destroyed and the Separatist's refueling capabilities crippled.
Having already dealt a serious blow to the Confederacy's ability to fight, Skywalker then took to the sky in an LAAT/i gunship, destroying a heavy gun turret laden outpost that was holding down a substantial number of the assault's clone forces―both infantry and several armored AT-TE walkers―with suppressive fire, along with supplying the main Separatist army with further reinforcements. He would also pursue two Vehicle Armored Carriers through a narrow canyon while they were en route to drop more Separatist automata on the battlefield; Skywalker destroyed them both before either could unload its cargo. Kenobi then tasked his Padawan with aiding a squadron of Delta-7 starfighters rid the Separatist command center of the numerous gun turrets that were preventing LAAT/i gunships from landing troops. Once Skywalker and the other pilots had eliminated the command center's anti-aircraft capabilities, Kenobi deployed a squadron of gunships to land at the center.
Once on the ground, clone troopers rapidly disembarked from the gunships' crew bays and stormed the battlefield. The planet's military citadel―which could be accessed through a land harbor nearby―was the site of a CIS sensor station. Skywalker ordered an AT-TE to penetrate the harbor. The Separatists tried to defend their walls with battle droids and four Armored Assault Tanks, but the gun turrets that were built onto the barracks were quickly destroyed and clone troopers soon poured into the harbor from all sides, including a side tunnel hollowed out within a network of several icy caverns. The sensor station soon fell to the Republic.
Meanwhile, Skywalker moved on, leaving the command center and citadel in the capable hands of the clone trooper. As he approached the temple, weaving through a high-walled canyon of ice, he discovered a massive convoy of Separatist vessels consisting of numerous large Multi-Utility Transports with AATs moving at their flanks. Kenobi warned that should the convoy reach the Jedi monument, the Republic army would be vastly outnumber and so Skywalker quickly engaged the convoy, battling them from the air until every last tank was destroyed. Their threat removed, Skywalker joined up with the main bulk of the Grand Army's ground forces at the monument, finding a Lucrehulk-class Core Ship and three Hardcell-class transports. Skywalker destroyed the Hardcell transports while, at Kenobi's order, two squadrons of LAAT/c gunships swooped down to deploy two armored AT-TE platoons as defensive support for twin SPHA-T artillery walkers assaulting the Core Ship.
Once the Core Ship was brought down under concentrated fire, Skywalker landed the gunship, and proceeded to enter the Jedi Monument in a fighter tank. Before he could proceed any further, he had to defeat the Spectral Guardians protecting Ulic's tomb. After defeating the guardians, Skywalker reached the ancient tomb of Ulic Qel-Droma within, where he alone learned how to withstand the effects of the Dark Reaper. With his new knowledge, Anakin declared the battle over and departed from the planet, leaving the CIS in defeat.