After invading the Esper World following the Battle of Thamasa and the extermination of most espers, Emperor Gestahl and Kefka Palazzo raise the continent as a floating base where the Warring Triad rest. After the Returners stationed in Vector escape the Empire, they attack the continent with Setzer Gabbiani's airship, the Blackjack. The Imperial Air Force surrounding the continent attempts to stop them, but is destroyed, allowing an away team to land on the continent's western tip.
The battle is an in-game event, in which the player forms a party of three and fights a series of battles against the Imperial Air Force. After several battles, Ultros and Typhon 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.
With the Air Force destroyed, the Returners can freely come and go on to the continent. It became the last Returner victory over the Empire; as Gestahl now aims to control the world with the magic of the petrified Warring Triad, he is no longer in the need for troops or an air force, rendering his military irrelevant. Kefka has other plans, however; he aims to get rid of Gestahl and absorb the power of the Triad, essentially becoming a God. Doing so will alter the alignment of the statues, and as their alignment defines the shape of the world, catastrophe awaits if they are moved. Both the Returners and Emperor Gestahl fail to stop Kefka, and in the subsequent end of the world both the Returners and what remains of the Gestahlian Empire are mostly wiped out.