The Lord of the Rings' appendices included tons of interesting lore, including an aspect of Aragorn's story that the novel's author deemed crucial.
A fan theory connects Gandalf to a group whose origins were not fully explained either in Peter Jackson's films or J. R. R.
But first, a little housekeeping: they didn't bother putting a campaign in Black Ops 4, and Black Ops 3 is set in 2065, so likely has no bearing on the next game. Frankly, I'd happily be brainwashed ...