The Rebel Alliance operated an efficient and widespread intelligence network of Bothan Bothan spies. Through this network, the Alliance learned of the construction of the Death Star, an extremely powerful space station capable of annihilating entire planets with its superlaser. Rebel prisoners aboard the Death Star managed to riot and got control of a technical readout while Imperial-turned-Rebel Kyle Katarn retrieved further plans. The final piece of the plans were recovered by Bria Tharen and the Red Hand Squadron during the Battle of Toprawa. From there they beamed it to Leia's ship, the Tantive IV, while the 501st Legion, under Darth Vader, tracked Rebels to Polis Massa, however this was only a set-up for the Empire. Even so, the Rebels, who fought with the defensive upper hand, were c