A timeline of all major events in the Halo universe from the time of the Forerunners through the rule of the Created.
The Algolis Invasion was a Covenant attack on the human colony world of Algolis in the Algol system sometime between 2548 and 2552.
The Battle of Gamma Pavonis VII was a small skirmish over the planet of Gamma Pavonis VII in the Gamma Pavonis system in early 2550.
The Glassing of Minab was a Covenant attack on the outer colony world of Minab in 2550.
The Defense of Concord was an attack by an unknown Covenant force on the colony of Concord, sometime in 2551.
The Battle of Ballast was a conflict between Covenant and UNSC forces on and around the colony of Ballast in 2551 or 2552.
Operation: FIRESIDE was an ODST mission to investigate a distress call sent by civilians on the colony world of Ariel, which had come under attack by Covenant forces days earlier in late December 2551 or early January 2552.
The Battle of Fumirole was a conflict between Covenant and UNSC forces on the colony Fumirole, April 22nd, 2552.
The Battle of Beta Eridani was a Covenant assault on UNSC forces in the Beta Eridani system, shortly before the summer in 2552.
The Massacre of Troy was a Covenant invasion of the colony of Troy in the Hellespont system approximately five months prior to the Battle for Earth.
The Battle of New Jerusalem was a Covenant attack on the colony of New Jerusalem in the Cygnus system sometime in July or August 2552.
Operation: RED FLAG was a planned operation by both the Office of Naval Intelligence and the UNSC to use Spartans to capture a Covenant ship, use it to penetrate into Covenant space, and capture a Hierarch, with the intent of using the Prophet to broker a cease-fire.
The Battle of Sigma Octanus IV was a large-scale space and ground battle between UNSC and Covenant forces in the Sigma Octanus system in July 2552.
The Fall of Reach was possibly the largest battle during the Human-Covenant War, taking place in the Epsilon Eridani system, in orbit and on the ground of Reach, humanity's largest military stronghold.
The Raid on Verge was a covert mission undertaken by Spartan-II Black Team to infiltrate and destroy a Covenant mining and refinery operation on the recently invaded former colony of Verge towards the end of July 2552.
The Battle of Line Installation 1-4 was a conflict on Line Installation 1-4, a Forerunner defensive facility that was part of the Jat-Krula, the Forerunner's version of the Maginot Line during the Forerunner-Flood war in August 2552.
The Battle of Tribute was a large-scale invasion of the colony world Tribute in the Epsilon Eridani system by Covenant forces during and after the Fall of Reach in 2552.
The Massacre at Eridanus Secundus was a Covenant attack on a rebel facility within a series of asteroids in the Eridanus system in late 2552.
Operation: FIRST STRIKE was a mission undertaken by John-117 and several other Spartan-IIs to infiltrate and destroy the Covenant space station Unyielding Hierophant and associated armada of over 500 warships in the Tau Ceti system prior to the Covenant's invasion of Earth.
The Battle of Installation 04 was an engagement between the UNSC Pillar of Autumn and the Covenant Fleet of Particular Justice on and around the Forerunner megastructure known as Installation 04, or Alpha Halo, in the Soell system.
The Battle for Earth was a large-scale space, air, and ground battle between the invading Covenant forces and the UNSC Home Fleet on and around Earth at the end of 2552.
The Skirmish on Mona Lisa was a minor conflict that occurred in the debris field of Installation 04 in the Soell system aboard the prison ship Mona Lisa between UNSC forces and an outbreak of the Flood on October 25th, 2552.
The Onyx Conflict was a major engagement between UNSC, Covenant, and Forerunner forces on and around the planet of Onyx in the Zeta Doradus system in October and November 2552.
The Battle of Installation 05 was an engagement between the Covenant forces, including those that fled the Battle for Earth, High Charity, and the Second Fleet of Homogeneous Clarity, and the UNSC-allied forces, including the UNSC In Amber Clad led by Miranda Keyes, and the Fleet of Retribution led by the Arbiter Thel 'Vadam.
The Great Schism was a conflict between the forces loyal to the Covenant, led mostly by the Jiralhanae, and the Sangheili, beginning on November 3rd, 2552 and continuing off and on until the Rule of the Created in 2558.
The Battle of Installation 00 was a major conflict between the forces stationed aboard the UNSC Forward Unto Dawn and Arbiter Thel 'Vadam's Fleet of Retribution, and the Covenant fleet loyal to the Prophet of Truth.
Operation: SUNSPEAR was a mission to infiltrate Covenant space and destroy a major population center as an act of revenge for the Fall of Reach at the end of 2552.
