Battle over the Floating Continent

The Battle over the Floating Continent was a conflict between the Empire and the Returners over the Floating Continent. After invading the Land of Espers, Emperor Gestahl and Kefka Palazzo raised the continent into the air as a floating base where the Statues rested. After the Returners stationed in Vector narrowly escaped the Empire, they attacked the Continent with Setzer Gabbiani's Airship Blackjack. The Imperial Air Force surrounding the continent attempted to stop them, but was destroyed, allowing an away team to land on the continent's western tip.

The battle is actually an in-game event, in which the player forms a party of 3 and fights a series of battles against the Imperial Air Force. After several battles, Ultros and Chupon fly to the ship. After battling them, the party is blown off the ship into a battle with Air Force, after which they land on the continent.

Although Ultros attacks the ship during the raid, it is neither confirmed or denied if he is an ally of the Empire or if his attack just happens to take place at the same time. Although there is no reason for Ultros and the Empire to ally, it is not entirely impossible either.

Aftermath
With the Air Force destroyed, the Returners were able to freely come and go on to the continent, eventually allowing them to confront Kefka and Gestahl at the continent's summit.