WARNING: The following contains spoilers for Star Wars #15 from Marvel, on sale now.
The Rebellion dealt some extreme blows to the Empire during Star Wars' Original Trilogy. While the Battle of Endor in Return of the Jedi was the tipping point in the Galactic Civil War, the destruction of the Death Star in A New Hope inspired the Rebellion to push on. The Death Star's destruction also made heroes out of Luke Skywalker and Han Solo. Star Wars has now revealed that Luke was present for another Rebellion victory and this one helped solidify the Rebellion's efforts.
Starlight Squadron has still not found a way to rescue their lieutenant Shara Bey, thus Luke has volunteered to assist them on their missions in Star Wars #15 by Charles Soule, Ramon Rosanas, Rachelle Rosenberg, and Clayton Cowles. They had been trying to locate the rest of the Rebel fleet when they dropped out of hyperspace just outside the planet Ab Dalis. They immediately received fuzzy communication from a Rebel base on the planet's surface, which informed Starlight Squad that they were under attack by an Imperial Star Destroyer.
Many of the Rebels felt that Starlight consisted of too few ships and that they were doomed, but others felt inspired by Luke's presence. While Luke was considered one of the Heroes of Yavin, the Rebels knew that he had destroyed the Death Star by exposing a unique vulnerability. Star Destroyers were a much more true and tested technology. They had no known vulnerability, especially one that could be exploited by X-wings. Facing imminent destruction, the ground team sent up coordinates for Starlight Squadron to aim their blasters. They suddenly went radio silent. Starlight was confused since the coordinates appeared to be a mountain on the planet's surface. Regardless, Luke flew towards it and discovered a vent. He became distracted when he was lining up his shot. He saw a vision that showed a failed attempt at destroying the Death Star. This caused him to lose focus and miss his shot.
Luckily another member of Starlight Squadron made good on their attempt, hitting the target which was revealed to be a dormant volcano. This caused an explosion that engulfed and destroyed the Star Destroyer. Their victory was incredible considering the odds yet their spirits were raised ten-fold when they realized who they saved. Mon Mothma, the leader of the Rebel Alliance was within the base on Ab Dalis.
This victory came at a particularly harsh time for the Rebellion. They are well removed from the events of A New Hope and many Rebels were beginning to lose hope. The Empire had cracked their communication codes which had separated the fleet. Han Solo had been recently frozen in carbonite and their rescue attempts had proved fruitless. Things were looking worse than ever for the Rebellion but their victory over the Empire on Ab Dalis surely reignited their spark.
The fact that Mon Mothma was within the base also adds to the importance of Starlight Squadron's actions. While Luke, Leia, and Han were generals of the Rebellion and performed many of the heroic actions, Mothma oversaw all of the Alliance's operations. Her death could have ended the Rebellion, especially during a time when they were divided. It would have been impossible for anybody to step into her role when the majority of the Rebel fleet simply does not possess the current communication codes.
The Death Star was destroyed during an attack by the Rebellion. The Rebels would have been set back if they failed, but all hope would not have been lost. On the other hand, Starlight Squadron was on the defensive when they helped out on Ab Dalis. Even though they might not have realized it at the time, the Rebellion might not have been able to recover if they failed. Their actions saved the leader of the Rebellion while inspiring hope for any who needed it.