Halo Alpha
Halo Alpha

The Massacre of the Outer Colonies,[3] also known as the Outer Colony Massacres, were a series of engagements during the early portion of the Human-Covenant war.[4]


The Insurrection[]

Main article: Insurrection

Prior to the appearance of the Covenant, the UNSC and CMA were knee deep in brush wars with angry colonists.

Prelude at Harvest[]

Thinking the planet had been constantly ransacked by Insurrectionists, the Office of Naval Intelligence sent Jilan al-Cygni to investigate the planet. In reality, freighters near Harvest were being boarded by members of the Covenant. 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 Harvest[]

SSgt Avery Johnson, UNSC Marine Corps

Avery Johnson leading Colonial Militia against the Covenant at Harvest.

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.

Early Losses[]

FoR - Archer missiles

The UNSC Commonwealth fighting the Unrelenting at Chi Ceti IV.

On November 1, 2525, the UNSC went to full alert and stripped the CMA of its forces, giving them to NAVCOM and UNICOM.[1] 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. The beginning of 2526 saw the destruction of Bliss.[5]

Cole Fights Back[]

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. Almost immediately after this recent conflict at Harvest, Biko was attacked by the Fleet of Inexorable Obedience.[6] In April, Circinius IV was assaulted. This resulted in the loss of one of UNSC's top military schools, the Corbulo Academy of Military Science.[7]

Following the attack on Circinius IV, ONI projects were refocused to solely counter the Covenant. As well, ONI Section Two sent emissaries to 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.[8]

After that, Madrigal was lost.[9]

Battle of Alpha Aurigae

Cole engages the Covenant at Alpha Aurigae.

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[10] and XI Boötis A.[11] The Covenant still managed to attack Hat Yai, despite these UNSC victories.

Continuing Losses[]


UNSC forces retreating at Arcadia.

By January 1, 2530 the casualties in the Outer Colonies had amassed to a total of 62,154,022 deaths.[2] 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 attacked by the Fleet of Glorious Interdiction but not glassed,[12] leaving the planet mostly to nature.[1] Arcadia was the last known battle the famed UNSC Spirit of Fire participated in before officially being listed as "Missing in Action." Vodin was lost in 2532,[13] 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.[14] Refugees from the Outer Colonies also had begun fleeing to the Outer Fringes trying to escape the Covenant's wrath.[15]


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.[16]

The colonies who got glassed took roughly 30 years to be habitable again. For example, in 2558, Bliss was a mining planet.[17]





  • The UNSC strips down the CMA of their resources and divides it among NAVCOM and UNICOM.[1]
  • The Battle of Chi Ceti takes place.





  • The Battle of Circinius IV takes place.[7]
  • ONI projects are repurposed to exclusively fight the Covenant. ONI Section Two warns Outer Colony leaders of the Covenant, and negotiations for ceasefire begin. ONI is rejected until footage of Bliss is shown.[8]






  • At this point, there have been a total of 62,154,022 deaths in the Outer Colonies.[2]