The seeds of the Blooding Years began immediately after the end of the Great Schism and the Human-Covenant war. In January 2553, the Arbiter Thel 'Vadam began to visit the various states to propose a peace treaty with humanity. He argued that too many Sangheili had been lost in the Great Schism, and that Sanghelios had to be rebuilt. This proposal was not well received by all, and civil unrest ensued. Dissident Sangheili began to join the Servants of the Abiding Truth, an old orthodox religious group who opposed the Arbiter led by Avu Med 'Telcam.
In February 2553, Fleet Admiral Terrence Hood arrived on Sanghelios to formalize the cease-fire with the Arbiter. They met in the state of Vadam and formally ended hostilities, solidifying the Treaty of 2552.
- Main article: Assault on Vadam
After a Jiralhanae rebellion began in Ontom, the Servants of Abiding Truth decided it was the time to strike against the State of Vadam. This assault was met with massive resistance including forces from the Swords of Sanghelios and the UNSC Infinity. The attack would ultimately fail with the Servants eventually retreating to New Llanelli.
Fighting broke out all throughout Sanghelios as rogue Keeps rose up to fight the Arbiter's Swords of Sanghelios. The Servants of Abiding Truth used New Llanelli as their base of operations throughout the rest of the war. The fighting was mainly between the Swords of Sanghelios and the Servants of Abiding Truth, but Jul 'Mdama's Covenant and rogue Keeps joined in on the fighting.
At one point, the women and children of a Keep were left behind as the males went off to fight the Arbiter. A human, whose name was Evan Phillips, was teleported to this keep when looking for Forerunner ruins. Kilo-Five was sent in to extract him, and he was extracted amidst a battle. He later learned that the women and children were massacred, which upset him deeply.
This fighting lasted for five years until the year of 2558 that involved Human intervention. In January of 2558 ONI sent in a prowler and SPARTAN-G059 to assassinate Avu Med 'Telcam, the leader of the Servants of the Abiding Truth. She succeeded and assassinated him, which crippled the Servants. Later on, in October, Jul 'Mdama's Covenant was fighting in the Battle of Kamchatka and Fireteam Osiris was sent in to kill Jul 'Mdama. After a brief fight, Jul 'Mdama was assassinated.
With the loss of their leader, the Covenant was also crippled. The Swords of Sanghelios began to attack the remainder of the Covenant strongholds, with the assistance of Fireteam Osiris. Finally, the Covenant were pushed back to their final stronghold, Sunaion
- Main article: Battle of Sunaion
After the losses encountered during the Battle of Kamchatka, the Swords of Sanghelios decided that the they were going to strike at Jul 'Mdama's Covenant's final Sanghelios stronghold at Sunaion. They launched a full scale invasion of Sunaion and this resulted in a big battle, in the air as well in the city itself. However, the Covenant had Anti-Aircraft Turrets that denied the Swords of Sanghelios to land troops in the city. However, thanks to Fireteam Osiris' help, they were able to destroy these turrets. The tide of the battle turned towards the Swords of Sanghelios as they were able to destroy most of Jul 'Mdama's Covenant as the battle went on.
However, towards the end of the battle, Promethean troops began to join the fight as the Guardian under the city began to awaken. This Guardian was just what Fireteam Osiris was looking for, and they made haste to board it. They met up with the Arbiter as the Warden Eternal appeared to join the battle until he was defeated and they boarded the Guardian. The Arbiter bid them farewell as the battle, and the war itself, came to a close.
- ↑ 1.0 1.1 Halo Waypoint - Universe - Locations - Sanghelios
- ↑ Halo 5: Guardians - Osiris
- ↑ Halo: Tales from Slipspace - Knight Takes Bishop>
- ↑ Halo: Glasslands - page 777
- ↑ Halo: The Thursday War - page 155, 156, 168
- ↑ Halo: The Thursday War - page 321-331
- ↑ Halo: The Thursday War-pages 209-368
- ↑ Halo Waypoint: Universe - Locations - Sunaion