HiddenMaster you make many great points. But I do not see why the Covenant would board the DS like this with around 7200 Tie fighters attacking. They would go through Slipspace into the center of the DS where the Empire have no defenses. I think that the core chamber of the DS/DS2 is big enough to hold a small Covenant fleet.
The Empire would never know what hit them.
I disagree. How would the Covenant know that the inside of the DS is hollow? They only way they would know that is if the got the plans, which would mean teaming up with the rebels, which I think is unlikely. The rebels are already fighting to free the galaxy from one oppresive government, why would they team up with another one who commited genocide on a bunch of humans, and refuse to allow any religion aside from their own? If anything, I would think that the rebels would team up with the UNSC.
And even if they got hold of some plans, I doubt the idea to jump in the middle of it. After the Elites left, they didn't really have any tactical geniouses. They probably would have gone for the all-out frontal assault, and gotten massacred in the process. The Covenant didn't know how to use the full abilities of their technology, either
Even if they managed to destroy the DS, it wouldn't mean the end of the Empire. After all, it survived the destruction of the first DS, and the only reason it collapsed after the second one was destroyed was because the Emperor went down with it.
One, they occupied a large portion of the galaxy and would only be out numbered about 4 to one vs the Empire
I think the Empire would have outnumbered them by a lot more than that. According to that article that I linked to above, the Covenant had part of the Orion arm (which Earth is a part of) of the Milky Way. According to this arcticle, the Milky Way has 4 major arms, with at least 2 minor ones, and one of those minor ones is the Orion arm. So the Covenant only had part of one small arm, while the Empire has an entire galaxy. Assuming that the Orion arm is 1/2 the size of a normal arm, that the Milky Way is about the same size as the one in Star Wars, and that they both have the same number of ships per sections of galaxy, the Empire would outnumber the Covenant by about 10:1.
Granted, some of that would have to go towards stopping rebelions, etc, but that still leaves a huge advantage for the Empire.
One for one, the Covenant would no doubt win land battles with the Empire, but the Empire would more likey prevail by numbers alone. They had billions, maybe even trillions, of Stormtroopers. The Covenant would only have a fraction of that, and the majority of their army would be grunts.
Even if numbers weren't enough to win the ground, the Empire would still have the DS, Eclipse, etc to annahilate the planet.
Personally, I think that the Halos themselves should be disregarded from the discussion. Sure, they're a superweapon, but you don't really win when you use it. Your enemy dies, but so do you, so activating them would be incredibly stupid.
Whew! Sorry for the wall of text.