Halo Alpha
Halo Alpha

The Siege of the Inner Colonies was a series of engagements taking place in humanity's Inner colonies.[1][3]


Main article: Outer Colony Massacres

Prior to Covenant attacking the Inner colonies, the Covenant had laid siege to the Outer Colonies for about a decade. Planets like Harvest and Arcadia had been attacked, killing millions in the process. The UNSC had stripped away most of the Colonial Military Administration,[1] becoming humanity's main military force.

In 2530, following the Battle of the Great Bear, Admiral Preston Cole would devise the basis of the UNSC Emergency Priority Order 09881A-1 or the "Cole Protocol".[4] This order was devised to help make sure the Covenant would not find the inner colonies, and was mostly the reason why it took so long.[5]


On June 1st, 2536, the Covenant Empire finally made their way into the Inner Colonies.[1]

Numerous ships were pulled from their positions in the Outer Colonies to defend the Inner Colonies.[6] Old ships, such as the Halcyon-class light cruiser UNSC Pillar of Autumn, were refitted and brought back into service to supplement the remaining defense forces.[7]

Early Battles[]

One of the earliest battles in the Inner colonies was the Battle of Camber. 5.5 million people were killed in the battle, and the planet was glassed.[8] Nearly a decade later, Miridem would come under attack leading to the capture of Dr. Catherine Halsey.[9] Actium would fall[10] with Skopje[11] at about the same time. In a rare moment, the colony of Ballast would come under attack and the UNSC would win the battle.[12]

The Fall of Reach[]

Main article: Fall of Reach
“We knew this day would come. They have found our fortress among the stars.”
— Catherine Halsey[13]
H2A Cinematic Reach-CovenantEngagingAutumn

The destruction of Reach.

The Fall of Reach was one of the greatest defeats in the Human-Covenant war.

In 2552, the Covenant had discovered Reach.[14][15][16] The Covenant initially landed on the planet with a smaller fleet,[17] but it began to escalate as more and more combatants arrived on either side. Dozens of Inner Colony planets were bypassed by the Covenant Fleet attacking Reach.[18] While Reach would end up being destroyed, a cruiser, the UNSC Pillar of Autumn, would escape the destruction and begin the decisive Battle of Installation 04.[19]

It can be presumed that even more inner Colonies survived, considering the next Covenant attack was Earth.

The Battle of Earth[]

Main article: Battle of Earth
“Earth...is all we have left.”
H2A Cutscene BattleofEarth

The Battle on Earth rages on.

After almost 27 years of war and the effort of most of humanity, Earth finally came under attack by the Prophet of Regret in late 2552. Earth's orbit would become the first area to be besieged, before the Prophet would move onto New Mombasa.[21] The Prophet would then use slipspace to fast travel out of New Mombasa[22] and to Installation 05.[23] Other Covenant forces would eventually move onto Ross Island, Havana, Cleveland, and Pawa. When the Keyship carrying the Prophet of Truth and John-117 returned to Earth,[24] his forces would use the crater created by Regret to dig up The Artifact.[25] This artifact would eventually lead to Installation 00[26] and the end of the war.


The loss of many of the inner colonies had a severe impact on the remaining UEG. The loss of Tribute alone would have a severe economic impact on human space.[27] On top of this, the Inner colonies that were hit hard by glassing would take some time to come back up to full health. Reach wouldn't become habitable until 2589.[28]


List of Engagements[]




June 1[]
  • The Inner Colonies are entered by the Covenant.[1]





  • The Battle of Actium ends.[10]




July 24[]


August 30[]
  • The Fall of Reach ends with Reach's glassing.[29][30]


October 10[]
October 20[]


November 17[]
  • The UNSC and Separatist forces travel to the Ark from Earth.[34]


December 5[]
  • One of the final battles on Earth takes place.[2]



  1. 1.0 1.1 1.2 1.3 1.4 Halo Wars - Collectible: Halo Wars Timeline Events
  2. 2.0 2.1 Halo Legendary Crate - Bonus Item: Naval Records Archives
  3. Xbox.com: Halo Storyline (Defunct, Copy on HBO Forums and Wayback Machine)
  4. Halo Wars: Genesis - pages 8-9
  5. Halo: The Fall of Reach - page 135
  6. Halo: The Fall of Reach, page 190 (Digital)
  7. Halo: The Fall of Reach - Page 272 (Digital), 238 (Physical)
  8. 8.0 8.1 Halo 2: Anniversary - Terminal: ONI File: Honor Bound
  9. 9.0 9.1 Halo: Ghosts of Onyx - Chapter 20: Page 173
  10. 10.0 10.1 10.2 Halo Waypoint: Videos - Hero (Courage) (Defunct, Copy on Youtube)
  11. 11.0 11.1 Halo: Evolutions - Essential Tales of the Halo Universe - Dirt: Page 313
  12. 12.0 12.1 Halo Encyclopedia - Page ??
  13. Halo: Reach - ViDoc: A Spartan Will Rise
  14. Halo: The Fall of Reach - Page 251 (2010)
  15. Halo Encyclopedia - Page 208 - The Fall of Reach
  16. 16.0 16.1 Halo: Reach - Level: Winter Contingency
  17. Halo: Reach - Level: Nightfall
  18. Halo: The Fall of Reach, page ??
  19. Halo: Combat Evolved - Level: The Pillar of Autumn
  20. Halo 3 - Level: Floodgate
  21. 21.0 21.1 Halo 2 - Level: Cairo Station
  22. Halo 2- Level: Metropolis
  23. Halo 2 - Level: Delta Halo
  24. Halo 2 - Level: The Great Journey
  25. Halo 3: ODST - Level: Coastal Highway
  26. Halo 3 - Level: The Ark
  27. 27.0 27.1 Halo Waypoint: Universe - Locations - Tribute
  28. Halo: Reach - Level: Lone Wolf
  29. Halo 2 - Level: The Heretic
  30. Halo: Reach - Level: The Pillar of Autumn
  31. Halo Legendary Crate - Bonus Item: First Twelve Hours
  32. Halo 2 - Level: Outskirts
  33. Halo: Uprising Issue 1
  34. Halo 3 - Level: Floodgate
  35. Halo: Fractures - Into the Fire, page ??
  36. Halo 5: Guardians Limited Edition - Bonus Item: Kelly-087 Dossier Card