Timeline of the Battle for Zeta Halo

This is a timeline of the events during the Battle for Zeta Halo. Fighting initially began on December 12, 2559 and has proceeded to June of 2560. Events on Installation 07 coincide with several Post-Covenant War conflicts including the Battle of Earth (2559), Battle of Boundary, Battle of Suban, and the Battle of Nysa.

December 12, 2559

• A Banished fleet led by Atriox arrived at Installation 07 and began building fortifications on the ring.
• A fleet of UNSC vessels led by the UNSC Infinity is ambushed by Banished forces over Installation 07. The Weapon is deployed to the ring. Captain Thomas Lasky orders all hands to abandon ship.
• John-117 engages Atriox in a hangar onboard the Infinity and is thrown into space. The ship is presumed destroyed.
• The surviving Infinity crew make landfall on the ring. Fireteam Taurus disables two Banished Kywasky Workshop Gorespike cannons in an area south of the Silent Auditorium.

December 13, 2559

• In an effort to stop the Banished from taking control of the ring, Cortana detonates an explosion from the Silent Auditorium, fragmenting Installation 07 and killing herself and apparently Atriox in the process. Various UNSC survivors on the ring's surface attempt to escape the destruction. Cortana's explosion unwittingly levelled the playing field in the fragmented section of the ring by taking out the third and last Banished Gorespike cannon.
• During the destruction event, Cortana initiated an emergency translocation protocol. Installation 07, along with the debris from the space battle, were transported away from the Ephsu system to an unknown location in a different star system in uncharted space.

December 15, 2559

• Spartan Vedrana Makovich discovers the crash site of the UNSC Mortal Reverie and determines it to be a viable location for the UNSC's base of operations.

January 20, 2560

• Spartans Bonita Stone and Nina Kovan scout out the Banished territory Red Zone, deducing a potential vulnerability of the enemy in that infighting is encouraged. They deduced that only Escharum's leadership keeps them in check.

January 23, 2560

• Spartan Hudson Griffin leads Spartans Panago, Malik, and Sarkar on a mission to assassinate Escharum. Spartan Bertold Vettel takes over his place and joins Commander Etana Hensler to lead the forces at the Reverie.

January 30, 2560

• Spartan Griffin's team is ambushed by Escharum and all are killed except for Griffin. Escharum taunts him of his team's demise and of the Banished's impending assault on the Mortal Reverie. Griffin is able to send out an encoded message, warning the UNSC survivors at the Reverie.
• The survivors at the Reverie receive a part of Griffin's transmission and prepare for an assault by the Banished.

January 31, 2560

• Banished Jiralhanae Chieftain Tremonius and Captain Arthoc gathers a massive Banished assault force at Riven Gate. Spartan Stone and Boulder Squad conduct a recon sweep at Riven Gate. Stone reports her findings to Mortal Reverie, and warns the Reverie that the Banished would arrive by nightfall.
• The UNSC survivors at the Mortal Reverie prepare for the Banished assault. Spartans Makovich and Vettel discuss the UNSC's inability to win the upcoming battle and their dwindling options for the future.
• Banished forces arrive at the Reverie and begin their assault on the wreckage.

February 2, 2560

• The Reverie's starboard side sustains heavy damage and its Rampart point defense guns are destroyed; Banished air units overwhelm UNSC forces.
• Spartan Vettel orders the UNSC survivors to retreat from the Reverie under the Banished assault. The survivors scattered and fled into mountains or the surrounding area. Many are killed or captured by Banished pursuers.

March 3, 2560

• The UNSC loses all of its remaining Forward Operating Bases on the fragmented section of the ring.
• Unofficial squads such as the Boat crew, Gravediggers, and Hatetriox have been taking out Banished supply runners, raiding parties, towers, bridges and other Banished structures.
• Spartans Makovich, Vettel, and Sorel declare the enactment of Rubicon Protocol.

April 18, 2560

• Using Lucas Browning as a Reclaimer, the Banished release the Harbinger from her cylix.

April 22, 2560

• Having observed aircraft from Escharum's personal fleet flying towards Outpost Tremonius, members of the boat crew—including Nina Kovan, Bonita Stone, TJ Murphy, Erik Bender, Robin Dimik, and Isaiah Cameron—investigate the outpost.

April 23, 2560

• After Spartan Stone shares that she saw Browning at Outpost Tremonius, Spartan Kovan attempts to rescue Browning during the evening, to no avail.
• Separated from Kovan following their escape from the outpost, Stone explores the subterranean Forerunner structures. She sends a transmission to Makovich and Sorel that the Banished are sending forces to another excavation site.

April 24, 2560

• Spartans Makovich and Sorel observe Banished activity around the Conservatory and realize the Banished are looking for Installation 07's monitor.

April 26, 2560

• Spartan Stone, while in the subterranean structures, finds the cylixes holding the Xalanyn. She picks up a UNSC signal deeper inside the facility. She finds Gorian and Jega 'Rdomnai accessing the Conspectus network data; Stone attacks the excavation team, stealing the data node, but was killed by 'Rdomnai during her escape. Before she was killed, however, Stone order her personal AI Ouco to copy the data into a data crystal chip and corrupted the original node, rendering it useless when 'Rdomnai recovers the date node.

April 29, 2560

• After confronting Kovan, Murphy leads the boat crew and infiltrates the subterranean structure underneath Outpost Tremonius. They discover Stone's body and recover the data chip containing the Conspectus network data. After they escape deeper into the structure, they met 091 Adjutant Veridity, who reveals the nature of the data. The boat crew agrees to release 117649 Despondent Pyre from lockdown at the Conservatory to decrypt the data.

April 29, 2560

• Spartan Vettel sends out a signal to any remaining UNSC transmitters that he intends to assault Chak Lok's fortress and rescue Spartan Griffin.

May 3, 2560

• While en route to the Conservatory, the boat crew reunites with Spartan Tomas Horvath. They decide to use one of ring's beacon towers as a supraluminal communications array to broadcast the ring's location to UNSC space and summon reinforcements.

May 9, 2560

• 117649 Despondent Pyre is released from lockdown by Spartan Horvath at the Conservatory's cradle.
• After learning of the Harbinger's release, Pyre gives the boat crew a data key that will allow them to broadcast a superluminal message into human-occupied space.
• Pyre refuses Veridity's request to follow the boat crew to a beacon tower; the monitor and her sub-monitors formulate a plan to counter the Harbinger.

May 14, 2560

• The boat crew accesses one of the ring's beacon towers and broadcasts Zeta Halo's new coordinates to UNSC space.
• Murphy, Cameron, and Gorian are all killed in the battle at the beacon tower. Spartan Horvath is teleported to an isolated location on the ring via a translocation pad, which is destroyed by a Thrasher missile.
• The surviving members of boat crew—Kovan, Bender, and Dimik—are rescued by 091 Adjutant Veridity and teleported to another location on the ring.

May 15, 2560

• Spartans Makovich and Sorel follow the Banished into the Conservatory with the intent to stop them from finding the monitor.
• Inside the Conservatory, the two Spartans encounter Jega 'Rdomnai. Makovich stays behind to hold off the Sangheili and tells Sorel to go on without her. She is killed by 'Rdomnai.
• The wounded Sorel encounters a Banished force led by Hyperius and Tovarus. He manages to take out multiple Banished troops before being slain.

May 25, 2560

• Far from any surviving UNSC personnel, Spartan Horvath makes a final transmission on UNSC channels that he is leaving Banished territory to look for survivors and Fireteam Intrepid. He makes an open plea to the Master Chief that they need him now more than ever.

Between May 28 and May 31, 2560

• John-117 is recovered from the remnants of the battle between the UNSC Infinity and the Banished by Echo 216 and its pilot, Fernando Esparza.
• The Ghost of Gbraakon discovers Echo 216 and uses its stasis beam to pull the Pelican aboard. John-117 leaves the Pelican and boards the Gbraakon, overloading its engines, destroying the ship. Escharum is made aware of John-117's survival.
• John-117 recovers the Weapon underneath the surface of Installation 07 and defeats Tremonius. Outpost Tremonius returns to UNSC control.
• Under the command of Escharum, Chak 'Lok activates Spartan Griffin's distress signal to lure John-117 to his Tower. John-117 defeats Chak 'Lok inside his Tower and learns of a Banished mining operation into the Conservatory thanks to Spartan Griffin, who dies of his torture.
• The Weapon helps John-117 defeat Bassus at the Excavation Site and shut down the drill preventing entry into the Conservatory.
• The Weapon learns of a mysterious entity worse than the Flood recovered from a past exchange between Cortana and 117649 Despondent Pyre prior to the arrival of the UNSC Infinity.
• John-117 meets the Harbinger, whose plans are to free the Endless from the Cylixes.
• John-117 and the Weapon learn that the Harbinger and the Banished are planning to repair Installation 07 through Reformation Spires.
• Echo 216 gets shot down by 3 Banished AA cannons en route to the Command Spire.
• John-117 disables the AA cannons and defeats both Hyperius and Tovarus.
• The Harbinger springs a trap on the Weapon while extracting the data needed to enter the Command Spire.
• John-117 liberates FOB Kilo, shuts down the Banished operations at Riven Gate as well as Annex Ridge, and eliminates the Mgalekgolo pair known as Myriad.
• While exploring the Command Spire, more of Cortana's past actions are revealed, including her role in the destruction of Laconia Station at the hands of the AI Leonidas.
• John-117 shuts downs all of the Spires, but Esparza is captured by Jega 'Rdomnai.
• En route to the Pilot's rescue, the Weapon discovers that Cortana destroyed Doisac because Atriox refused to join the Created.
• John-117 survives the House of Reckoning, kills Escharum and rescues the Pilot.

May 31, 2560

• John-117 and the Weapon discover the true purpose of the Silent Auditorium, the site of Cortana's sacrifice, and defeats the Harbinger. However, the Harbinger succeeds in discovering the location of her people and transmitting it to an unknown recipient. Atriox would at some point locate the Endless in their Cylixes.

Between May 31 and June 3, 2560

• The Banished recaptured multiple UNSC FOBs that the Master Chief had taken.
• As retribution for Escharum's death, the Banished communication towers broadcast orders to execute UNSC prisoners, while some members of the Banished turned on their human-led factions. While Escharum's death left a power vacuum, rumor had it that a new leader would take his place on June 4, the last day of Escharum's funeral.
• While searching for the Master Chief and the Weapon, Echo 216 located a wrecked but still partially inhabitable Mulsanne-class light frigate in the debris field and set up camp, dubbing the wreckage the UNSC Casa del Esparza.

June 3, 2560

• Three days have passed since the Harbinger's demise and the subsequent collapse of the Silent Auditorium. John-117 and the Weapon emerge elsewhere on the ring, having seemingly travelled forwards in time to three days later. Echo 216 picks up John-117 and the Weapon to return to the fragmented section of the ring.
• The Weapon chooses the name Joyeuse for herself while Echo 216 identifies himself as Fernando Esparza.
• Esparza takes the Master Chief and Joy to his camp in the wrecked frigate he found to rest and regroup.

June 4, 2560

• The Banished's upper echelon gather for Escharum's funeral and it's revealed that Jega 'Rdomnai is still alive and holding Lucas Browning captive.
• The Master Chief and Joyeuse destroy the House of Reckoning with an Eris tactical nuclear weapon, killing at least most of the Banished gathered, although some may have escaped.

June 5, 2560

• The Master Chief raids Rdomnai Keep, rescuing combat medic Lucas Browning from Jega 'Rdomnai's clutches.
• Hoping that a change of tactics will allow him to learn the Harbinger's secrets from Browning, 'Rdomnai allows the escape in favor of following from a distance.

June 6, 2560

• Under attack by Banshees, Echo 216 is joined by Spartan Tomas Horvath who aids in fighting the attack off and informs the group of the boat crew's distress signal to the UNSC.
• Browning reveals that a geas was implanted into him by the Harbinger, leading to a change of mission to uncovering the mysteries implanted in Browning's head.
• Departure of Horvath in a captured Banshee to draw away pursuing Banished forces.
• Discovery by the Master Chief, Joy, Esparza and Browning of a large encampment of fifty-two survivors -- a mixture of military, support, science and civilian -- led by Commander Wes Thompson at Lifeworker Central.
• With Banished gathering on the camp's perimeter, the Master Chief's group departs for the Lifeworker Archive while combat teams lead the Banished away.

June 8, 2560

• Funeral of Lucas Browning.
• The Master Chief's group, four Swords of Sanghelios and the group of survivors with the boat crew join the UNSC encampment at Lifeworker Central.

Between June 8 and June 11, 2560

• Accompanied by Spartan Kovan, the Master Chief continues guerilla operations against the Banished, climbing into the hills beyond the jungle around Lifeworker Central, taking Banished patrols by surprise, clearing outposts and then blending back into the jungle.
• The UNSC breaks through a hidden access point into a network of chambers extending multiple levels underground at Lifeworker Central.

June 11, 2560

• With the help of Joyeuse, Dr. Genie Dawson and her team are downloaded into a scavenged submonitor carapace.
• Jega 'Rdomnai discovers from Rises High that Despondent Pyre's encephalon was taken by the Master Chief's AI, preventing him from using it to try to seize control of the ring.

June 12, 2560

• Although unable to locate the Infinity, Genie and her team find signs of large groups of other survivors in several areas, more than any of them had seen on the ring so far. While still facing enormous odds, with additional forces, the UNSC could launch a concerted effort and make more of an impact. The camp at Lifeworker Central prepares for search and rescue operations.
• A Swords of Sanghelios relay satellite outside of the Urs system picks up the boat crew's transmission containing Zeta Halo's coordinates and an embedded UNSC distress signal. Arbiter Thel 'Vadam shared this discovery with Spartan Olympia Vale. For the first time, the UNSC is aware of what happened to the Infinity following her departure in December, opening up the possibility of reinforcements being sent to Zeta Halo.