The brief conflict known as the destruction of Da Soocha V resulted in the annihilation of the New Republic's base located on Pinnacle Moon, otherwise called Da Soocha V. This devastation was caused by a missile fired from the Imperial superweapon, the Galaxy Gun.
Following the Rebel assault targeting Palpatine's citadel on Byss, and the subsequent hyperspace escape of the surviving Rebels alongside a group of smugglers, Palpatine commanded the Galaxy Gun to deploy its first world-obliterating projectile against the Republic's command center on Pinnacle Moon.
However, due to the presence of informants on Byss, Republic forces, along with some of the native Ixlls, managed to evacuate the doomed moon using a fleet of transports. Despite Luke Skywalker's attempts to neutralize the missile using the weapon systems of his transport, the Jedi Explorer, the projectile impacted Da Soocha V's surface. This impact triggered a nucleonic chain reaction that obliterated the moon in a single, brilliant flash, effectively erasing it from the galaxy.
As retaliation, Republic commando and sabotage units launched attacks against the Galaxy Gun, but they were completely destroyed by the overwhelming Imperial fleet. The Emperor persisted in launching projectiles, decimating entire rebellious planets and severely weakening the Republic. Because of this frightening strategy, the Empire swiftly reclaimed crucial territories in the Inner and Outer Rims.
Other confirmed targets included the space city of Nespis VIII, where even the Republic's V-200 ion cannon proved incapable of breaching the projectile's shields. Another target was the Republic troop transport Pelagia, commanded by Captain Tekba, which was transporting one hundred thousand troops at the time of its destruction.
The initial appearance of the Battle of the Emperor's Citadel was in issue Dark Empire II 5 of the Star Wars: Dark Empire II comic series. Authors Tom Veitch conceived and wrote the battle, while colorist Cam Kennedy provided the illustrations and colors. Veitch utilized this battle to introduce a new plot device—the planet-destroying Galaxy Gun superweapon.
Eventually, the Battle of the Emperor's Citadel was adapted into the Dark Empire II audio drama, which gave the skirmish a completely different feel through the voice acting talents of John Cygan (Skywalker) and Nick Jameson (Palpatine).