In the interview the director has stated that FUD takes place before the Covenant-Human war and deals with the Insurrection. The problem is that it shows the Chief in Mjolnir armor but in the books the Spartans only get the armor at the beginning of the Covenant-Human war. So how does the Chief have his armor?
Don’t the Covenant come down to the academy and it is the Beginning of the Covenant-Human war?
It starts before the war, and ends at the start of the war.
The characters in FUD are training to fight Innies, just as the Spartans were. Then the War breaks out, the Spartans get MJOLNIR, after which the Chief shows up and saves them or whatever. I don’t see it being an issue.
It covers a time period, not just a day.