Battle of Genesis

The Battle of Genesis was a battle fought between UNSC Spartans, Servants of the Abiding Truth who replaced Jul 'Mdama's Covenant and the Promethean Created forces of Genesis in October 2558.

Prelude
After seeing a vision from his thought-to-be-deceased AI companion Cortana, Spartan-II John-117 headed to the planet Meridian with the rest of Blue Team to find her. Declared AWOL by the UNSC, Spartan-IV Fireteam Osiris led by Jameson Locke was sent to retrieve them. Osiris tracked Blue Team into an underground Forerunner structure and caught up with them but they managed to escape into a nearby Guardian. Osiris retreated as the Guardian entered slipspace over the planet.

The battle
After arriving on Genesis, a Forerunner Builder installation serving as a link to the Domain, Blue Team fought their way through Covenant forces who had crashed landed there. They eventually reached a structure where they encountered the Warden Eternal. The Warden introduced himself as Cortana's defender and questioned John-117's motivations while simultaneously deploying several waves of Prometheans to confront the Spartans. After an extended battle, Blue Team were able to defeat the Prometheans, destroying one of the Warden's bodies in the process. Immediately afterward, Blue Team were contacted by Cortana, who informed them of her intention to uphold the Mantle of Responsibility. John voiced concern over the fundamental nature of the Mantle, which were quickly dismissed by Cortana. Fighting their way through several more Promethean squadrons, Blue Team eventually reached the structure known as the Gateway, described as a link between Genesis and the Domain.

Following closely behind them was Fireteam Osiris, who had arrived at Genesis on a Guardian from Sanghelios. With them was 031 Exuberant Witness, the monitor of the Genesis installation. After fighting through the battling forces of the Covenant and Prometheans, Osiris finally reached Blue Team's location, where they encountered two Wardens. After dispatching the Wardens, Osiris headed inside and offered to help Blue Team stop Cortana. Before they could do anything however, Blue Team was transported to the Domain, where they fought through Prometheans and three Wardens before finally reaching Cortana's location. John pleaded Cortana to come back with him, but Cortana refused and placed Blue Team inside a Cryptum. Learning what happened, Osiris moved to destroy the gravitational cores holding the Cryptum in place, while fighting Covenant and Promethean forces. After destroying the last core, Osiris followed Exuberant to the main core. Taking an elevator down, Osiris made there way to the core but were slowed down by a Guardians concussive blasts. Locke finally reached the core and destroyed it, but he was too late, Cortana had secured the Cryptum and was prepared to leave. However, before she could, Exuberant sent hundreds of Constructors who forced the Cryptum from the Guardians grasp just before it entered slipspace. The Constructors opened the Cryptum and Blue Team was reunited with Osiris, who promptly exfiltrated them.

List of appearances

 * Halo 5: Guardians
 * Halo Mythos: A Guide to the Story of Halo