In the year 2525 on the human colony world of Harvest, a 28-year conflict between humanity and the alien collective known as the Covenant began. It was the most devastating conflict humans had ever been involved in. In the end, billions of human lives were lost during the war. Colonies were destroyed, worlds were rendered uninhabitable, and yet, because of one Spartan, humanity endured, survived, and ultimately won.
Halo: Reach
Released: September 14, 2010, for Xbox 360
July 24, 2552. The Human-Covenant War reached toward its climax. The Covenant secretly invaded the planet Reach, the most important world to the United Nations Space Command—its nerve center. The Spartans of Noble Team were sent to investigate a silenced communications relay, only to discover the Covenant presence on the planet, which was hidden by means of sophisticated stealth technology. Over the next month, Noble Team fought valiantly but was cut down one by one in the face of overwhelming odds. Eventually, only Noble 6, the newest member of the team, stood alone in the face of the impending glassing of the world. Before joining the rest of Noble Team in death, the Spartan was able to deliver the AI Cortana to the UNSC cruiser Pillar of Autumn and the waiting Master Chief. The vessel made its escape from the slaughter, with a Covenant fleet in pursuit.
Halo: Combat Evolved
Released: November 15, 2001, for Xbox
Re-Released: November 11, 2014, Master Chief Collection for Xbox One
September 19, 2552. The Pillar of Autumn was unable to escape the Covenant despite performing a blind slipspace jump. As they returned to normal space, they found a gas giant planet called Threshold. Orbiting it was Halo: an impossibly massive ring structure, built by the Forerunners more than 100,000 years ago. The Covenant had beaten the Pillar of Autumn to the Halo, and the ship was forced to deploy its Marines and the Master Chief to the ringworld and execute a crash landing. The Covenant engaged the humans in battle throughout the ring, and the Master Chief played an instrumental role in the fighting.
Eventually, he and the AI Cortana discovered that the Halo was part of an array of similar installations placed throughout the galaxy. The Halo Array itself was a weapon of last resort against a virulent parasite known as the Flood, which was sealed on the ringworld for study by the Forerunners. If fired, the Halos could wipe out all life in the galaxy. The Covenant unwittingly unleashed the parasite across the ring, and both they and the humans incurred heavy casualties as a result. In a desperate bid to destroy the Flood and escape the Halo, the Master Chief returned to the crashed Pillar of Autumn and set it to self-destruct. This shattered the ring and seemingly ended the Floor threat. The Master Chief made a narrow escape with Cortana.
Halo 2
Released: November 9, 2004, for Xbox
Re-Released: November 11, 2014, Master Chief Collection for Xbox One
October 20, 2552. The Master Chief returned to Earth and was decorated as a hero. Meanwhile, the Covenant Elite who led their forces in battle upon the Halo was deemed a heretic by the Covenant leadership. The Covenant Prophet of Regret, on a mission to discover new Forerunner artifacts, stumbled across the planet Earth and, despite being outnumbered, assaulted the human homeworld and managed to occupy the African city of New Mombasa. The Master Chief led a successful counterattack that drove the Prophet of Regret off-world and brought the Earth a moment’s reprieve. The Master Chief, along with the UNSC fleet, pursued the Prophet of Regret.
The Prophet of Regret discovered a new Halo, also known as Installation 05. During these events, the disgraced Elite commander was named an Arbiter, a representative of the will of the Prophets, and was unleashed against the Covenant heretical rebels who wished to be free of the Prophets. The Arbiter, betrayed by Tartarus, the leader of another Covenant species known as the Brutes, eventually joined forces with the Master Chief after many battles and more shocking revelations. Halo 2 also contained the Flood parasite, but it was no longer merely hordes of mindless souls absorbed into the collective. Rather, this Flood had a central mind, a Gravemind. Worse yet, the Covenant, now led by the Brutes, intended to fire the Halo Array to initiate the Great Journey, as their religion demanded. They were now at open war with a significant Separatist movement, led by the Elites. Ultimately, the Master Chief and the Arbiter prevented the firing of the Array, killing Tartarus in the process. Unfortunately, Cortana was left behind on the Covenant mobile homeworld of High Charity, where the Flood Gravemind resided and was beginning to expand its already countless army.
Returning to Earth aboard a Forerunner Dreadnought controlled by Covenant forces loyal to the Prophet of Regret, the Master Chief prepared to finish the fight.
Halo: ODST
Released: September 22, 2009, for Xbox 360
Re-Released: May 30, 2015, Master Chief Collection for Xbox One
October 20, 2552. During the Prophet of Regret’s invasion and subsequent retreat from New Mombasa on Earth, the UNSC deployed its elite Orbital Drop Shock Troopers (ODST) into the war zone. One team was in mid-drop just as the Prophet’s assault carrier executed a slipspace jump in the Earth’s atmosphere. The rookie of this team, separated from his comrades, fought his way through New Mombasa alone for several hours before reuniting with his squad and encountering a member of another Covenant species, the Huragok. The new alien signaled its willingness to work alongside its UNSC captors out of hatred for its Brute oppressors.
Meanwhile, the Covenant occupation of Earth continued, and the excavation of New Mombasa revealed an enormous Forerunner installation that had been dormant for millennia.
Halo 3
Released: September 25, 2007, for Xbox 360
Re-Released: November 11, 2014, Master Chief Collection for Xbox One
November 17, 2552. The Master Chief returned to Earth and joined up with UNSC survivors and the Arbiter, who leads the Elites, which have now fully turned against the Covenant. After a series of battles, the combined forces struck at the Forerunner artifact found buried underneath the city of New Mombasa, where the Prophet of Regret had landed the Forerunner Dreadnought. The artifact produced a massive slipspace portal through which the Covenant retreated. Simultaneously, a Covenant cruiser filled with the infectious Flood crashed into the African city of Voi.
After the immediate Flood threat to Earth was contained, Master Chief learned that Cortana had left a message aboard the crashed ship. She described a solution to the Flood that did not involve firing the Halo Array: Beyond this portal was the Ark, a massive Forerunner facility located outside our galaxy. A combined UNSC-Elite task force, including the Master Chief and the Arbiter, left Earth through the portal to pursue the Prophet of Regret to the Ark, thereby beginning a desperate fight to prevent the Array from being fired.
After many battles, the Arbiter ultimately had his vengeance. Meanwhile, the Flood crashed the mobile homeworld High Charity into the Ark and threatened to overwhelm the forces gathered there. It was discovered that the Ark facility manufactured Halo rings that later dispersed themselves to key points within the galaxy, and that it was currently crafting the replacement for the destroyed Installation 04. The Master Chief saw this as an opportunity to destroy the Gravemind. To fire the replacement Halo, he first had to retrieve Cortana from the Gravemind’s clutches. Fighting their way to the Halo’s control room, Cortana used the Activation Index retrieved from the first Halo to fire the weapon.
The Master Chief and the Arbiter raced to the UNSC frigate Forward Unto Dawn in an attempt to escape the Halo’s firing and the destruction of the Ark. Unfortunately, the slipspace portal collapsed mid-jump, sundering the frigate in half. The forward half, containing the Arbiter, made it back to Earth. The aft half of the vessel, containing Master Chief and Cortana, was left stranded in an unknown part of the galaxy.
With rescue unlikely to be anytime soon, the Chief prepared to enter cryosleep, knowing that he might drift for years. Cortana activated a beacon, advising him that it might be a while before anyone responded, to which he replied, “Wake me when you need me.”
On Earth, the Arbiter, his Elites, and the surviving UNSC forces mourned the apparent loss of humanity’s greatest hero.
Halo 4
Released: November 6, 2012, for Xbox 360
Re-Released: November 11, 2014, Master Chief Collection for Xbox One
June 27, 2557. Four years after the Master Chief and Cortana went missing in action, the ruined portion of Forward Unto Dawn drifted into the gravitational pull of a mysterious Forerunner planet called Requiem. Cortana woke Master Chief from cryonic sleep shortly before the Dawn’s remnants were caught in Requiem’s gravity well and forced into a crash-landing.
As Chief and Cortana explored Requiem, Cortana revealed that she was experiencing “rampancy,” a declining mental state that leads to inevitable death. Chief promised to get Cortana to Earth, believing that Cortana’s creator, Dr. Catherine Halsey, could fix Cortana’s condition.
Chief and Cortana soon picked up garbled transmissions from another UNSC ship, the Infinity, which tracked the Dawn’s distress call. In an effort to warn Infinity of Requiem’s gravity well, Cortana directed the Chief to deactivate what she believed to be communications jammers—but the Chief unwittingly released an ancient Forerunner warrior known as the Didact from imprisonment instead. The Didact attacked Infinity after it was dragged onto Requiem by the gravity well. Chief made contact with Infinity and helped repel the Didact’s attack.
In the process, Chief was contacted by a Forerunner known as the Librarian, who explained that the Forerunners were divided on how best to combat the Flood. The Librarian reveals that the Didact used a device called a Composer to convert the warriors under his command into digital versions immune to infection—constructs known as the Prometheans. The Librarian, who has guided humanity’s development, accelerated the Chief’s evolution to grant him immunity to the Composer.
The Master Chief was ordered to retreat back to Earth, but he disobeyed orders and stayed behind to oppose the Didact. Infinity executive officer Commander Lasky gave Chief an armed transport and wished him luck. Chief and Cortana followed the Didact to a Halo ring, Installation 03. The Composer had been moved to the nearby Ivanoff Research Station, which the Didact retrieved and used to compose every individual on the station except the Chief.
Chief and Cortana used a fighter to follow the Didact’s ship through slipspace toward Earth. Aided by Infinity, now commanded by Lasky, and the UNSC home fleet, the Chief boarded the Didact’s ship with a nuclear warhead. With the help of Cortana, the Chief defeated the Didact, who fell into a slipspace corridor generated underneath the Composer. The Master Chief activated the nuke but was saved by Cortana, who sacrificed herself. The Chief was found by a UNSC rescue team and was taken back to Infinity, where he, mourning the loss of Cortana, talked with Lasky about Earth, humanity, and the meaning of a soldier’s duty.
Halo 5: Guardians
Released: October 27, 2015, for Xbox One
October 25, 2558. Set several months after the events of Halo 4, Halo 5: Guardians continues the unfolding story of the Reclaimer saga. A brief period of peace is shattered when colony worlds are suddenly and unexpectedly attacked. Humanity needs the aid of its greatest hero once again, but the Master Chief has gone missing, prompting Spartan Jameson Locke to hunt him down—an act that initiates an epic adventure with consequences that threaten to redefine life for the entire galaxy.