The mission to Kashyyyk was one step in the Rebellion's plan to keep the Empire away from Echo Base.
A Rebel team, led by Han Solo and Chewbacca, went to Kashyyyk to fool the Imperials in their attempts to find Echo Base. After defeating several beasts in the forest, they found their way to Rwookrrorrro. They had to prove themselves in the arena and gain the Wookiees trust. However, a group of mercenaries discovered the Rebels and led the Imperials to Rwookrrorrro. While fending off the Imperials and smugglers (not to mention a variety of beasts), they managed to activate the village's shields. After defeating Bossk, Luke Skywalker's X-Wing crashed and he was found by the other Rebels perfectly fine. Then they stormed the Imperial camp. After defeating one of the commanders stationed there, they found the codes. Then they made a hasty retreat of Kashyyyk. Their next stop was Ord Mantell.