>>11013705No energy shields, inferior slipspace drives (3-5 lightyears a day and large errors in exit location vs 2000+ a day, formation exits, and in-atmosphere transitions for covenant drives), inferior acceleration and propulsion, and inferior hull armor.
Oh, and inferior numbers; IIRC the Covenant had more CCS class battlecruisers (Truth and Reconciliation's class) than the UNSC had warships. Keep in mind, High Charity alone had an armada of almost a thousand ships, and the Unyielding Heirophant had another 500+, plus shields explicitly stated to be strong enough to withstand the impact of a small moon. Another couple hundred ships were vaporized when the NOVA took out Joyous Exultation. Cole's last stand took another 100 with him.
With very few exceptions the UNSC needed 3-1 odds to win a fight. The battle of Reach was almost 4-1 in the Covenant's favor, and once the ODP groundside generators were knocked out, they could approach and begun glassing. There's also the fact it became SOP of the Covenant fleet to do a precision jump in and take out the ODPs if there aren't too many of them to prevent them from killing ships.
If the UNSC had time, yes, they probably would have turned it into a straight fight and won the war that way, but they never got it. Had the Pillar not jumped to Installation 04 and events there and afterwards transpired (First Strike), the UNSC would have lost the war.
