War for the Mantle of responsibility

"Humanity stands as the greatest threat in the galaxy. Refusing to eradicate them is a fool's gambit. We squander eons in the darkness, while they seize our triumphs for their own. The Mantle of responsibility for all things belongs to Forerunners alone. Think of my acts as you will. But do not doubt the reality: the Reclamation... has already begun."

- The Ur-Didact during the Human-Promethean war

Belligerents
63 years after the first contact with the Forerunner the UEG have completely recovered from the Human Covenant War. Encompassing 846 stars system and more than 76,6 billions humans. The United Sangheilian alliance is an inter species alliance regrouping the Sanheilis the Unggoy, the lekgolo and the Kig-Yar. Their alliance is composed of 1,400 worlds and 114 billions beings. In their the subsequent defeat in their failed assault on sangheilios and during the Human-Promethean war the Covenant Remnant went into hiding to rebuilt their force and formed an alliance with the Forerunner under the command of the Didacts council well over the explored territory of the Galaxy Both their population and world situation are unknowns.

Political Situation
The political situation of the galaxy has great evolved in 63 years. They are now one of the lead species of the galaxy. Since the Human-Promethean the UEG own several research station around the Halo rings and several which are now decommissioned. The technology advance made by the research made on the Forerunner installation is tremendous and are now incorporated in the human warships which are now able to travel across human territory witting a matter of days. The projectile technology is still used for the weapons but are now far more effective. The Spartan-IV are now a completely autonomous force with it own branch and are numbering around 200,000 operator. As for the Sangheilian alliance is the powerful ally of the UNSC it navy and weaponry has evolved but not as much as the human and maintain the same design, but it still extremely powerful and it capital is Sangheilios. UEG and the Sangheilian alliance maintain economical, military and scientific rapport. Their mutual rapport has been the key to the rebuilt of humanity.

April 30th
On April 30th the UNSC remote scanning post detect a ship signature identified as Mantle Approach a ship that was reported destroyed above Earth 63 years before. Whiting 5 minutes the signal is lost. It would be 2 hours later that the largest fleet ever detected would jump in the system and destroy the remote scanning post the last transmission was an quote from the Ur-Didact: "Humanity stands as the greatest threat in the galaxy. Refusing to eradicate them is a fool's gambit. We squander eons in the darkness, while they seize our triumphs for their own. The Mantle of responsibility for all things belongs to Forerunners alone. Think of my acts as you will. But do not doubt the reality: the Reclamation... has already begun." The War for the Mantle of Responsibility had begun.