Joseph Harper

Fleet Admiral Harper was a high ranking UNSC officer in 2552. During the First Battle of Earth, he commanded one of the fleets protecting Earth. He was most likely part of the Orbital Defense Grid over Africa, in charge of protecting the MAC orbital platform clusters in that region, which included Cairo Station. Fleet Admiral Harper was not seen on screen, however he was heard in two separate transmissions regarding the attack on Earth, by the Prophet of Regret's battle group (consisting of 15 Covenant Capital Ships: 13 CCS-class Battlecruisers and 2 Assault Carriers). Harper's transmissions were as follows:

Fleet Admiral Harper: This is Fleet Admiral Harper, we are engaging the enemy!

Fleet Admiral Hood: Negative Admiral. Form a defensive perimeter around the cluster.

Fleet Admiral Harper: First echelon, you're with me. Light up those cruisers. Take 'em out one by one. Second echelon, keep those carriers busy.

It is not known exactly how many ships are under the command of Fleet Admiral Harper; but the readout from Cairo Station stated that his fleet consisted of 8 Cruisers and 67 Frigates, as well as a large number of fighter units, as at one point he ordered his Longswords to blanket the Covenant cruisers and take them out one by one.

Though he has the same rank as Fleet Admiral Hood, Harper is his subordinate. This is due to the fact that as the Chief of Naval Operations, Hood is technically the highest ranking officer in the UNSC Navy.

Given the "smashed" status of the human fleet by the events of Halo 3, it is highly probable that Harper died in battle with the Covenant Loyalist Forces.