During the Galactic Civil War, specifically in 1 ABY, a Rebel Invasion of Kashyyyk met with failure. Darth Vader commanded an Imperial starfighter group that successfully stopped Rebel Alliance forces from landing on Kashyyyk with the intent of liberating it.
In the year 1 ABY, the Rebel Alliance organized a fleet and gathered troops, aiming to invade and liberate the Wookiee planet of Kashyyyk. Their goal was to free it from the control of the Galactic Empire and the Trandoshan slavers who were present. Unfortunately for the Alliance, the Empire discovered their plans just before the invasion was set to commence. Darth Vader, who happened to be on Kashyyyk at the time, quickly assembled Imperial starfighters and pilots to prepare an ambush for the incoming Rebel fleet. Although Vader himself did not directly participate in the combat, he made his personal Eta-2 Actis-class interceptor available to an Imperial ace pilot who had previously served under Admiral Krieg.
Imperial pilots, despite having minimal time to launch and coordinate within the Kashyyyk system, were prepared when the Alliance starfighters emerged from hyperspace. A squadron of X-wing starfighters was the first to arrive in the system. The Rebel pilots were completely taken by surprise, as they had expected to launch a surprise attack on Kashyyyk. The ensuing battle resulted in significant losses for the Alliance, particularly due to the Imperial ace flying Vader's interceptor.
Later, Rebel troop transports and support ships entered the system, but they were soon confronted by a contingent of Imperial TIE bombers. Having lost the majority of their X-wings in the initial engagement, the Alliance starships found themselves utterly defenseless against the Imperial fighters and bombers. All Rebel troops perished within their transports before they could even approach the atmosphere of Kashyyyk. The battle concluded with the destruction of the remaining Alliance vessels.
The annihilation of the Rebel invasion force in space eliminated any immediate prospects of liberating Kashyyyk. The Wookiee planet would remain under Imperial control until it was eventually freed three years later by the forces of the New Republic, following the pivotal Battle of Endor.
The Rebel Invasion of Kashyyyk was featured in the 2003 video game Star Wars Galaxies, a massively multiplayer online roleplaying game created by Sony Online Entertainment and distributed by LucasArts. The game was eventually shut down on December 15, 2011. The battle itself was incorporated into the game through the Rage of the Wookiees expansion pack, which was launched on May 5, 2005.