Massacre of the Outer Colonies

The Massacre of the Outer Colonies was the series of engagements that made up the early Human-Covenant War.

Harvest and the humanity's response
was tasked with investigating the silence of Harvest, but signals with it were soon lost too. The Colonial Military Administration sent Battle Group 4 to investigate the escalating situation. Arriving on October 7, 2525, the Battle group was attacked. Only the managed to escape. The Heracles returned to Reach on October 31st, relaying what had happened and a message: "Your destruction is the will of the gods, and we are their instrument."

The following day, on November 1, 2525, the Unified Earth Government began mobilizing the CMA and UNSC. Specifically, the UNSC went to full alert and stripped the CMA of its forces, giving them to NAVCOM and UNICOM. On November 2, the SPARTAN-IIs were deployed.

Early battles and losses
At some point immediately after the attack on Harvest, Green Hills and Second Base were attacked by the Covenant. On the 27th of November, Chi Ceti IV was assaulted by a Covenant ship at the same time SPARTAN-II forces were receiving their MJOLNIR Powered Assault Armor. Almost immediately after in December, the SPARTANs were reassigned to fight the Covenant at Alpha Corvi II.

The first year
The beginning of 2526 saw the destruction of Bliss. Soon after on March 1, Preston Cole in charge of UNSC Battle Group X-Ray fought the Covenant off over Harvest. Seven days later, Cole as well as others would devise Operation: SILENT STORM, part of which would involve laying a trap at Biko using Task Force Yama. At this point in time, the Covenant were only operating in the Polona Sector, Vevina sector, and Grenadi sectors. The colony of Etalan, with roughly 10 million people was also attacked during this time.

As part of SILENT STORM, the UNSC moved to position themselves at Seoba, over Biko and discovered an Insurrectionist plot to over the Bikon Chancellor. This would require the UNSC to go offensive before they would fight the Covenant. The Insurrectionists were driven back, but not before the Covenant arrived and attacked the planet. Almost a month after, the prestigious Corbulo Academy of Military Science on Circinius IV was destroyed, leaving only 3 survivors.

Only two days after 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.

Planets began falling two or three a week. The Office of Naval Intelligence was unable to collate intelligence at the rate of the Covenant's incursion. UNSC Fleet Command was unable to plan out grand strategies and thus granted operational autonomy to UNSC naval units.

In the summer, UNSC forces along with forces from the Children of Mesra fought the Covenant on Mesra.

At the end of the year, the UNSC and Covenant fought a large battle in the Alpha Aurigae system.

Pressing inward
The Covenant kept pressing ever inward into human space. In 2528, the UNSC continued to counter the Covenant at the Battle of XI Boötis A but Madrigal fell later in the year. Two years later in 2530, Eridanus II was glassed and the UNSC abandoned the planet. On December 24 of 2530, the UNSC and Covenant clashed at the Battle of the Great Bear. The battle would lead to the formation of the Cole Protocol.

The Arbiter
In February 2531, Arbiter Ripa 'Moramee, under the command of the Prophet of Regret, began leading searches for Forerunner technology to aid in the Covenant war effort during the end of the Harvest campaign and the Battle for Arcadia. With the Covenant having discovered the Forerunner shield world Etran Harborage sometime prior, the Prophet of Regret intended to use a fleet of s docked at the Apex Site to crush humanity "quickly and with ease." With Ripa having kidnapped Professor Ellen Anders at Arcadia to use as a Reclaimer to activate the shield world, he was pursued by the, leading to a battle at the Etran Harborage. In the battle, Ripa was killed by Sergeant John Forge who subsequently sacrificed himself to destroy the Etran Harborage by causing its internal sun to go supernova. The Covenant plan was foiled, but the Spirit of Fire sacrificed its slipspace drive to cause the supernova, leaving the ship and its crew stranded in deep space.

The Inner Colonies
On June 1, 2536, the Covenant had finally broken into the Inner Colonies. This would be the beginning of a multi-year siege of the most inner worlds of humanity.

Continuing losses in the Outer Colonies & refugees
By 2535, a number of Outer Colonies had been lost and refugees were beginning to pour into the Inner Colonies, such as on Chi Rho.

Other Outer Colonies also fell even after the Inner Colonies were being attacked. Meridian, came under siege for three years late into the war. As well, Arcadia was attacked a second time.

2525

 * The Battle of Alpha Corvi II takes place.

2526

 * Etalan is attacked by the Covenant.
 * Circinius IV and Corbulo Academy of Military Science are attacked and destroyed.
 * The Covenant attacked Mesra.

2528

 * The Battle of XI Boötis A takes place.

2530

 * Battle of the Great Bear takes place, leading to the creation of the Cole Protocol.

2531

 * Harvest campaign - In early February, the five year long Harvest campaign comes to an end following the Covenant failure to destroy the relic.
 * Battle for Arcadia - Having learned the location of the Outer Colony Arcadia from the Relic on Harvest, ships from the Fleet of Valiant Prudence attack Arcadia. Defending ships manage to destroy one of the two initial attackers while the helps repel ground forces. Later reinforcements end the battle in a human victory, though not with massive loss of life. Professor Ellen Anders is kidnapped by Arbiter Ripa 'Moramee.
 * Battle of the Etran Harborage - Battle between the and forces of the Fleet of Valiant Prudence attempting to gain access to the fleet of Forerunner s on the shield world Etran Harborage which would give the Covenant a massive tactical advantage. Death of Arbiter Ripa 'Moramee and the destruction of the Etran Harborage at the cost of Spirit of Fire's slipspace drive.