343i's Frank O'Connor Demos Halo 4 Campaign, Shares New Info On Covenant

You definitely saw the Covenant fighting the Prometheans there. The Prometheans were objecting to their presence on Requiem, which is the world the story takes place on. If you think about human society and human civilization, we're hardly monolithic. There are lots of different cultures and factions. You're going to find out about this particular faction and their particularly virulent form of the former Covenant with some really enthusiastic shall we say religious beliefs about the Forerunners.

And they never gave up hope. You can only imagine their delight and surprise when they find out at least some of their myths and some of their legends about the Forerunners turn out to be true. That's something they discover on Requiem initially in a surprising way, but the game will have a few twists and turns, so you'll definitely find out more about that both in the campaign and in Spartan Ops. That's a big part of the Spartan Ops story.