Ages of Reclamation

The Age of Reclamation is an era of Covenant history in which the true search for the Halos began. Curiously enough, the Covenant use of the term "Reclamation" in describing their search for the Halos, possibly hinting that the Covenant see themselves as affiliated with the Forerunners and worthy of "reclaiming" the Forerunner rings. The Ninth Age of Reclamation is the time in which the Human-Covenant War happens, and began when the Minister of Fortitude became the Prophet of Truth and declared war on the Human race. The Age of Reclamation is one of the seven stages of the Covenant seen in a Halo 2 deleted scene, where the Prophet of Truth shows the Arbiter the Covenant's history.

The Ninth Age of Reclamation
It should first be noted that the events of Halo: The Fall of Reach, Halo: The Flood, Halo: First Strike, Halo: Ghosts of Onyx, Halo: Combat Evolved, and Halo 2 all took place during the Ninth Age of Reclamation. It should also be noted that the events of Halo 3 did not take place during this Age.

Beginning
The Ninth Age of Reclamation took place during the Human-Covenant War. This Age began in the year 2525, the year that the Covenant came into contact with humanity for the first time at the UNSC colony world of Harvest. The world was filled with Forerunner glyphs, which the Covenant misinterpreted as "Reclamation". The true meaning, however, was "Reclaimer", and every human was covered with such a glyph, denoting them as the Reclaimers of the Forerunners. The Minister of Fortitude understood this revelation would destroy the Covenant, and thus ordered all humans to be destroyed for being a danger to holy Relics. He was also sure that the war would lead them to other Relics that they could reclaim, and finally the Sacred Rings.

The planet Harvest was immediately glassed. Spartan-II super soldiers were deployed in the Battle of Chi Ceti, boarding a Covenant Frigate, planting explosives on the ship, and destroying it. It should however be noted that the victory came at a high cost. The Master Chief's personal friend, Samuel-034 was killed when the nuclear devices confiscated from the Pelican dropship were detonated.

Human-Covenant War
In 2530, the Covenant Empire attacked and glassed Eridanus II, home world of the Master Chief. The Battle of Harvest then took place in 2531, the first major space engagement between the UNSC and the Covenant. The Covenant was outnumbered and the UNSC stood victorious, barely. In 2535, the Covenant destroyed Jericho VII in the Battle of Jericho VII, and by that year, the Covenant were winning decisive victories against the UNSC, crushing and decimating its Outer Colonies. By 2536, Covenant militants swarmed into the UNSC Inner Colonies. For several years, human lives were spent in huge numbers winning ground operations, only to be wasted after the Covenant won the battle in space, glassing the Inner Colonies one after another.

Then, in 2537, Spartan-IIIs were trained and deployed in the battles of New Harmony, New Constantinople, and the Siege of the Atlas Moons. In Operation: PROMETHEUS, Spartan-III Alpha Company was slaughtered by Covenant forces. Noted however, they managed to succeed in their goal of destroying the reactors on the moon. In 2544, the minor Battle of Miridem took place. In 2545, Operation: TORPEDO resulted in the massacre of Spartan-III Beta Company at Pegasi Delta.

Installation 04
In 2552, the Battle of Sigma Octanus IV lead to a major UNSC victory, but at the cost of the Covenant learning the location of Reach and Installation 04. During the Battle of Reach, the largest naval battle between the UNSC and the Covenant, Covenant forces won a decisive victory, destroying 152 UNSC ships and 20 Super MAC gun platforms. This was a major blow to the UNSC, who lost their last great stronghold, with the exception of Earth. A single UNSC ship, the UNSC Pillar of Autumn escaped to Installation 04. After four days of hard fighting in the Battle of Installation 04, the Covenant discovered the Flood organism and Forerunner constructs, which severely hampered their efforts to control the Installation. The melee ended with the destruction of Installation 04, an event that left only a handful of survivors.

Unyielding Hierophant
The Commander of the Fleet of Particular Justice(also known as the future Arbiter) tasked with defending Installation 04 was put on trial, marked as a Heretic to quell discontent within the High Council. Later, he became the Arbiter, embarking on missions to quell a Heretic insurgency, led by Sesa Refumeeand to retrieve the Index and the 343 Guilty Spark. Then, in Operation: FIRST STRIKE, Six SPARTAN-II super soldiers were able to rout and destroy all but a dozen or so of a fleet of 500 Covenant star ships in orbit around Unyielding Hierophant through the sacrifice of Admiral Whitcomb and Lieutenant Haverson on board Ascendant Justice. The survivors on board the UNSC Gettysburg surveyed the damage and jumped to Earth, scoring a major UNSC victory. The First Battle of Earth then occurred. Though a relatively small and lopsided battle (15 Covenant ships fighting 75 UNSC vessels and 300 MAC platforms) this event is significant in that the Covenant finally discovered the location of Earth.

Installation 05 and the end of the Ninth Age of Reclamation
The UNSC won the fight with the help of the Master Chief. A single Covenant ship, belonging to the Prophet of Regret, survived the First Battle of the Earth and retreated to Installation 05, also known as Delta Halo. The Covenant ship was pursued by a single UNSC ship, UNSC In Amber Clad. This resulted in the Battle of Installation 05. Again, a massive fight ensues between the UNSC, Covenant, Flood and Forerunner Constructs (Sentinels, Enforcers, etc). The Flood appear to have been in control of part of Installation 05. The onslaught of the Covenant Civil War ended the 9th Age of Reclamation. This has been referred to as the ninth and final age.

This extract of Covenant history was probably the most desperate and shocking time for the Covenant as all three of their main religious leaders were killed, and an entire species, the Sangheili, successfully broke away from the majority of the hegemony, taking with it an unprecedented amount of personnel, equipment, and territory.

Trivia

 * The Ninth Age of Reclamation was the only known Age where all of the Covenant Hierarchs die.
 * This was probably the worst period of time for the Covenant.