The Year is 2552, Humanity is at war with a fundamentalist alien conglomerate known simply as 'The Covenant'.
We are losing.
For the past 27 years humanity has been fighting a war where death or survival are the only two options. We are grasping at straws.
A ship is being constructed in the Oort cloud to hopefully turn the tide, but until then, all that stands in the way are millions of soldiers, marines, sailors, and pilots. Dying by the thousands.
For 27 years. A generation lost, but not all hope is.
Spartans, hailed as walking legends, their presence brings a bolstering of morale and a capacity for destruction nearly unmatched. They are used sparingly, in missions none other can possibly attempt to complete. Their numbers dwindling, they have been publicly acknowledged, to public view, none of them are dead. In reality, less than two dozen in total remain.
In months prior, UNSC's High Command and the enigmatic Office of Naval Intelligence crafted a plan to use the remaining Spartans to get far behind enemy lines, capture their leaders, and force a surrender. Billions of credits spent, thousands of work hours logged, and the greatest minds of a generation worked on an operation to get these legendary few to the enemy. But they were too late, by mere weeks.
Reach, the closest thing humanity had to a planetary sized military base, was found by the Covenant, and is undergoing an assault never before seen in this war. Limited engagements began in July, with a dire, yet still hopeful series of military offensives occurring until mid August, with the success of Operations Upper Cut and Left Jab there was a singular fleeting moment of hope that Reach would hold.
But right at the apex, all hope died. The largest fleet ever seen assembled by The Covenant appeared in orbit, The Fleet of Particular Justice. It is now August 23rd, the UNSC fleet at Reach is scattered at best, or molten slag at worst. The Covenant are ravaging cities, and glassing what isn't an active combat zone. Millions are dying, millions more will die, and all that can be done is to flee. Reach is lost, but the story of those still making a stand has only just started.
This is a story of the brave, happy few, who would journey into the depths of the void and back to give their species' future a hope. This is the twilight of the Human-Covenant War.