- Main article: Insurrection
Prior to the appearance of the Covenant, the UNSC and CMA were knee deep in brush wars with angry colonists. This had inadvertently helped give the UNSC and CMA new naval tactics, which would prove to be useful during battles with the Covenant.
Prelude at HarvestEdit
Thinking the planet had been constantly ransacked by Insurrectionists, the Office of Naval Intelligence sent Jilan al-Cygni to investigate the planet. The Covenant would then fall for a trap that Jilan and two UNSC trainers would set up. This confirmed that it was not Insurrectionists, but rather aliens. The three decided that they needed to prepare for a first contact scenario.
Opening at HarvestEdit
The disastrous first contact broke down into a heavily one sided battle. Local militia and UNSC training forces managed to mount an admirable defense and saved many civilians. Ultimately, the planet was glassed by a single Covenant vessel.
A scout ship, the CMA Argo was sent to investigate the planet. When the CMA lost contact with the Argo, Battlegroup 4 was assembled and sent to Harvest. Out of three ships in the group, one managed to limp its way back to Reach to tell of what was encountered.
On November 1, 2525, the UNSC went to full alert and stripped the CMA of its forces, giving them to NAVCOM and UNICOM. On the 27th of the same month, Chi Ceti IV was assaulted by a Covenant ship at the same time Spartan-II forces were receiving their Mjolnir Powered Assault Armor. That same year saw the loss of Biko, and the beginning of 2526 saw the destruction of Bliss. Following the attack on Bliss, ONI Section Two sent emissaries to other Outer Colony leaders to warn them of the Covenant and give them an offer: end hostilities with the UNSC and receive protection. Initially they laughed at the prospect, until they witnessed footage of Bliss.
Cole Fights BackEdit
The UNSC had Preston Cole lead a battlegroup to retake Harvest. He would win this battle, but a protracted military campaign would begin on the planet. The Covenant had already pushed on to Green Hills and Second Base. Following the first victory at Harvest, Circinius IV was assaulted. This resulted in the loss of one of UNSC's top military schools, the Corbulo Academy of Military Science. After that, Madrigal was lost.
Preston Cole continued to lead UNSC forces out in the Outer Colonies. He managed to score a more victories in the Battles of Alpha Aurigae and XI Boötis A. The Covenant still managed to attack Hat Yai, despite these UNSC victories.
By January 1, 2530 the casualties in the Outer Colonies had amassed to a total of 62,154,022 deaths. The UNSC would suffer another loss with the attack on Eridanus II. Though Preston Cole would score another victory at Groombridge 1830 system during the Battle of the Great Bear. This victory would lead Cole to create the "Cole Protocol" after interrogating a prisoner of the battle.
Arcadia was also attacked but not glassed, leaving the planet mostly to nature. Arcadia would be the last known battle the famed UNSC Spirit of Fire would participate in before officially being listed as "Missing in Action." Vodin was lost in 2532, and Jericho VII was lost along with Charybdis IX in 2535. One of the last battles before the Covenant breached the Inner colonies was at the [[Indra Asteroid Cluster at the end of 2535. Refugees from the Outer Colonies also had begun fleeing to the Outer Fringes trying to escape the Covenant's wrath.
After the Covenant destroyed a majority of the Outer Colonies, they began to press inwards on the UNSC, taking out the Inner Colonies. As well, some Outer Colonies would fall after these massacres, such as Meridian.
Some Outer Colonies managed to escape the Covenant altogether. Though with the retreat of the UEG and UNSC saw these planets face famine, plagues and social collapse. In some cases, these planets had local ecology just take over what was left on these planets.
- The First Battle of Harvest takes place.
- The UNSC strips down the CMA of their resources and divides it among NAVCOM and UNICOM.
- The Battle of Chi Ceti takes place.
- The Battle of Biko takes place.
- The Battle of Bliss takes place.
- The Battle of Circinius IV takes place.
- ONI Section Two warns Outer Colony leaders of the Covenant and negotiations for ceasefire begin. ONI is laughed off until footage of Bliss is shown off.
- The Battle of Alpha Aurigae takes place.
- At this point, there have been a total of 62,154,022 deaths in the Outer Colonies.
- The Battle of the Great Bear takes place.
- The Battle of Eridanus II takes place.
- The Harvest Campaign comes to a conclusion.
- The Battle of Arcadia takes place.
- The Battle of Vodin takes place.
- The Battle of Jericho VII takes place.
- The Skirmish at the Indra Asteroid Cluster takes place.
- The Battle of Charybdis IX takes place.
- ↑ 1.0 1.1 1.2 1.3 Halo Wars - Collectible: Halo Wars Timeline Events
- ↑ 2.0 2.1 2.2 2.3 Halo: Reach - Collectible: Data Pad 14
- ↑ Xbox.com Halo Storyline (Defunct, Copy on HBO Forums)
- ↑ Halo: Reach Limited Edition - Bonus Content: Excerpt From Accra Log
- ↑ 5.0 5.1 Halo: Reach Limited Edition - Bonus Item: Dr. Halsey's Personal Journal, April 28, 2526
- ↑ 6.0 6.1 Halo: The Cole Protocol - page 72
- ↑ Halo: Evolutions - Essential Tales of the Halo Universe, The Impossible Life and the Possible Death of Preston J. Cole - page 470
- ↑ Halo Wars: Genesis - page 6
- ↑ Halo Wars - Levels: Arcadia City, Arcadia Outskirts, Dome of Light, Scarab
- ↑ Halo Waypoint: Universe - Characters - Randall Aiken
- ↑ Halo: Reach Limited Edition - Bonus Item: Dr. Halsey's Personal Journal, November 22, 2535
- ↑ Halo: The Cole Protocol - page 25
- ↑ Halo Waypoint: Canon Fodder - Sustained Glass
- ↑ Hunt the Truth - BENJAMIN_GIRAUD_ENTRY_0384