A timeline of all major events in the Halo universe from the time of the Forerunners through the rule of the Created.
2142 CE
In 2142 CE, the Unggoy were discovered on their homeworld of Balaho by the Covenant and forcibly added to their list of member species.
The Jovian Moons Campaign was a brief conflict in 2160 between the corporate-backed Friedens and the neo-communist Koslovics on several of the Jovian moons, spurred by a Frieden attack on a team of colonial advisers sent by the United Nations to help police the often violent region.
The Rainforest Wars was a large-scale conflict from 2162 to 2163 between the fascist Friedens, the neo-communist Koslovics, and the forces of the United Nations on the continent of South America.
The Mars Campaign was a retaliatory strike in December 2163 by the United Nations to eliminate the Koslovics, a rebel organizations labeled as terrorists by the UN.
The Shaw-Fujikawa Translight Engine, informally known as an FTL drive or slipspace drive, was invented by a team of scientists led by Tobias Fleming Shaw and Wallace Fujikawa and unveiled to humanity in April 2291.
The first permutation of the Orion Project, the predecessor to the future Spartan programs in the 26th century, was initiated on April 13th, 2321, consisting of five test candidates.
The Domus Diaspora was a time period during humanity’s expansion into the galaxy that saw massive colonization efforts of hundreds of colony worlds in the span of around thirty years, starting in 2362.
The colony world of Reach, the first ever extrasolar colony established by humanity, was colonized sometime in 2362 by the colony ship Odyssey.
2462 CE
Following years of abuse of Unggoy at the hands of the Kig-Yar culminating in the sterilization of thousands via poisoning, the Unggoy Rebellion began in 2462 to protest their treatment by the Kig-Yar and the Covenant as a whole.
~2470 - 2480 CE
Sometime prior to the Jiralhanae’s inclusion into the Covenant in 2492, a decade-long civil war known as the First Immolation devastated the Brute homeworld of Doisac and reduced the Jiralhanae society to pre-industrial technologies.
In 2491, the Office of Naval Intelligence re-instituted the Orion Project, an attempt to create engineered super-soldiers to boost combat effectiveness.
2492 CE
In 2492, soon after the end of a devastating civil war between Jiralhanae that caused a total collapse in Jiralhanae society, the Covenant visited the Brute homeworld of Doisac and invited them to join.
Operation: TREBUCHET was a twelve-year UNSC operation to quell growing unrest and insurrectionist activities in the outer colonies from 2513 until the start of the Human-Covenant War in 2525.
The Spartan II program, led by Dr. Catherine Halsey, was a plan by the Office of Naval Intelligence to use children with superior genetic traits to create a group of super-soldiers in order to put an end to the ongoing Insurrection in the outer colonies.
The Battle of Chi Ceti was a battle between the UNSC Commonwealth and the Covenant vessel Unrelenting in the Chi Ceti system on November 27th, 2525.
Spartan-III Alpha company was the first of three Spartan-III companies to be recruited, trained, and put into service.
Operation: PROMETHEUS was an assault on a Covenant shipyard located on and around asteroid K7-49 by Spartan-III Alpha Company.
Spartan-III Beta company was the second of three Spartan-III companies to be recruited, trained, and put into service.
Spartan-III Gamma Company was the last of three Spartan-III companies to be recruited, trained, and put into service.
Operation: TORPEDO was a mission by Spartan-III Beta Company to infiltrate and destroy a Covenant refinery on Pegasi Delta, the moon of 51 Pegasi B in the 51 Pegasi system.
The Battle of Ballast was a conflict between Covenant and UNSC forces on and around the colony of Ballast in 2551 or 2552.
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.
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 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.
1342 CE
In 1342, Covenant ships arrived in the Y’Deio system, the home system of the Kig-Yar, finding a species with a penchant for piracy.
1112 CE
The Yanme’e were discovered by the Covenant during their search for Forerunner artifacts in 1112, sparking a short but violent conflict that eventually ended in the incorporation of the Yanme’e into the Covenant.
~97,745 BCE - 97,445 BCE
The Forerunner-Flood War was a military engagement between the Forerunner species and the Flood that took place over approximately three-hundred years from 97,745 BCE until 97,445 BCE.
~97,445 BCE
The Great Purification was the final event of the Forerunner-Flood War, purging the entire Milky Way galaxy of all sentient life, including Forerunners, the Flood, and any other species that may have survived the Flood infestation.
2200 BCE - 2100 BCE
The War of Wills was a fierce and prolonged conflict between two factions of the San’Shyuum: The Stoics who wanted to worship Forerunner technology but never use it, and the Reformists who wanted to take advantage of the incredible Forerunner artifacts around the galaxy.
938 BCE - 852 BCE
The War of Beginnings was an eighty-six year conflict between the San’Shyuum Reformists who escaped Janjur Qom after the War of Wills and the Sangheili species between 938 and 852 BCE.
852 BCE
The Writ of Union was a declaration of peace between the San’Shyuum and the Sangheili, as well as the formation of the Covenant, signed by both species in 852 BCE.
789 BCE - 784 BCE
The Taming of the Lekgolo was a five-year campaign by the Covenant to first destroy, and later incorporate the Lekgolo into the Covenant hierarchy from 789 to 784 BCE.
