The Battle of Bespin took place in the time around the Battle of Endor during the Galactic Civil War.
The gas giant Bespin, with its Cloud City and tibanna gas mines, was occupied by the Galactic Empire in 3 ABY. The city and mining operations were taken over, but only as small garrison was left. In addition, although tightly under the control of the Empire, it nonetheless was subject to some minor raids by the Rebel Alliance, with at least one occurring in 4 ABY before the Battle of Endor.
The battle rages in Cloud City.
The Rebel Alliance launched an attack on Cloud City. The battle raged both in the air and on the floating settlements of the gas-giant. It started at the capital, and moved outwards across the various gas-refineries as the Rebels continued to gain ground.
Down on the ground, Rebel soldiers captured the main carbon-freezing chamber and secured their command posts in the vicinity. The Imperial stormtroopers and snipers fell back under the Rebel's attack.
The SpecForce then moved on to capture the main Imperial mining platform.
The Rebel forces landed and secured the gas extractor, and pushed the Imperials back to the other side of the platform. The Rebel forces moved in and captured the Imperial docks and landing platforms, trapping them in the main command center. Y-wings bombed the building, X-wings destroyed Imperial starfighters before they could lift off, and the enemy numbers dwindled. Teams of SpecForce soldiers moved in on the command building and secured the mining platform.
Although the Imperial garrison was attacked, the city was not liberated until after the Battle of Endor in 4 ABY.
The battle appeared in the 2004 video game Star Wars: Battlefront in two consecutive Galactic Civil War era missions, although the storyline is said to be S-canon by Leland Chee, the Keeper of the Lucasfilm Ltd. Holocron continuity database. The player fights for the Rebellion in both missions. In the second mission, players or the computer may capture neutral Cloud Cars. Although the game's strategy guide includes maps of the battle sites, it does not include information on the Historical Campaign.