|We may belong to different nations and races!! But I ask any of you who do not wish to die to lend me your strength!! Please... I want to ensure our future together!! I want you to fight with me!! Against the devils on Paradis!!|
|— Willy Tybur calls the world to action|
The Global Alliance (世界連合 Sekai Rengō?) is a military union of a multitude of nations united in their efforts to prevent the world's destruction at the hands of Eren Yeager and wiping out all Eldians of Paradis Island.
The bulk of the Global Alliance's power lies in the Global Allied Fleet (世界連合艦隊 Sekai Rengō Kantai?). Consisting of the combined naval forces of participating nations, each vessel in the fleet is equipped with the most advanced artillery on the planet to combat the Wall Titans should they emerge to commence the Rumbling.
During a festival held in Liberio, Willy Tybur hosts a performance before a massive gathering of world ambassadors and politicians recounting the history of the Eldian Empire and the threat that Paradis Island poses in its current political state. Despite the peace desired by the royal family, Willy warns the world that the power of the Founding Titan has been usurped by Eren Yeager, ending Paradis's century of peace and once again making the possibility of a worldwide Rumbling cataclysm a real threat. Urging the nations of the world to unite with Marley against Paradis, Willy is then killed by the Attack Titan Eren himself along with many international ambassadors caught in the ensuing chaos. This act of war serves as the catalyst which unites the nations of the world against Paradis Island.
In the aftermath of Eren's raid on Liberio, General Theo Magath discusses the formation of the Global Alliance with the remaining warriors, stating they will be ready to launch an assault upon Paradis Island in six months' time. Unsatisfied with the length of necessary preparations, Reiner Braun proposes a smaller, immediate strike in order to catch Paradis off guard before they can take action to prepare for the Global Alliance's assault. Shortly before Marley's revenge for Liberio, Zeke Yeager escapes from Levi Ackerman's custody in order to reunite with Eren, fully aware of the imminent threat the Global Alliance will pose to both his plans and Paradis Island's existence.
When Eren and Zeke reunite and Eren unleashes the Wall Titans in a cataclysmic worldwide Rumbling, the Marleyan forces on Paradis depart immediately to warn the mainland of the incoming attack. The Global Allied Fleet establishes a defensive blockade along the northeast shore of the mainland. Despite carrying the most advanced artillery on the planet, the fleet's efforts prove useless against the advance of the Titans. The Titans capsize and destroy many of the Alliance's ships before setting foot on the continent.
Joining forces with the Warrior Unit and a fraction of the Survey Corps opposed to Eren's genocide, Yelena confesses that she had informed Eren a year prior of the likelihood of a Global Allied Fleet assembling in Marley's northern port city of Karifa, recommending it as the target of a partial Rumbling.
Three years after the end of the Rumbling, the surviving remnants of the allied nations select the Warriors and Survey Corps defectors responsible for Eren Yeager's death to serve as ambassadors to Paradis Island in order to negotiate peace talks.
Many generations afterward, Paradis Island is destroyed in a devastating military onslaught, though it is unknown whether or not the Global Alliance is involved in the conflict.