Operation: MACARTHUR

Operation: MACARTHUR was a joint United Nations Space Command and Sangheili Armed Forces strategic offensive against the Blood Covenant during the War of Vengeance from 2556 to 2558 in order to weaken the Blood Covenant's infrastructure and defensive capability in preparation for another great offensive in the same manner of Operation: TACK HAMMER. In conjunction with the UNSC's campaign of Unrestricted Prowler Warfare, this resulted in severe damage to the Blood Covenant's infrastructure and military-industrial complex, allowing the alliance to strike the final series of killing blows in Operation: FURY in 2560.

Prelude
The first action of the war, the attack on Unmoving Virtue was conducted with the cooperation of the Sangheili Armed Forces Second Fleet of Enlightened Benevolence, and the UNSC 30th Fleet. The battle was a significant victory for both participants, and saw the deployment of numerous new technologies. In this regard, it served as a combat test for UNSC prototypes, proving their reliability and effectiveness in the field, and also functioned as a psychological deterrent against further Covenant aggression. For the Sangheili, it saw the liberation of thousands of captured Sangheili slaves from the shipyards, the destruction of three significant Jiralhanae fleets, and denied the Blood Covenant control of a strategically important naval shipyard.

The attack also proved to be a double-edged sword for the UNSC/Sangheili alliance, however: Jiralhanae politics being what they are, the leadership annihilated at Unmoving Virtue were quickly replaced, and the other worlds put on immediate alert. Another attack of the same scale would not be possible again for many years, until the Blood Covenant fleet had been left battered and disparate after years of swift, aggressive and devastating raids against the most significant nodal points, leaving worlds dependent upon them to "wither on the vine", reminiscent of the "Island Hopping" campaign envisaged by World War II Admirals Nimitz and Halsey.

Pious Ascension (February 2556)
After the defeat at Unmoving Virtue, the Blood Covenant moved their capital to Pious Ascension. However, given the planet's position as a key shipyard, a large population centre, and a major stop-off point and re-fuelling base for convoys heading for four other smaller colonies, it was an obvious target for the Island Hopping campaign, something that the Blood Covenant leadership apparently failed to appreciate. The force defending Pious Ascension was larger than the alliance was prepared to comfortably deal with, however, and so they planted disinformation to convince the Blood Covenant that an attack was to take place at the less well-defended but equally important world of Eternal Fealty. The Office of Naval Intelligence made use of an easy-to-break code to transmit the information between fleet formations, and even constructed a faux attack fleet that seemed to be poised to assault Eternal Fealty. Blood Covenant cryptanalysists and intelligence officers were convinced that the attack on Eternal Fealty would come at any time, and so Blood Covenant Naval Command made the decision to detach three dozen ships from the Pious Ascension fleet to reinforce Eternal Fealty, giving the allies the opening they needed.

An allied force of sixty-four ships arrived at Pious Ascension on February 2, 2556 and engaged the far larger but technologically inferior Blood Covenant fleet, dealing them heavy damage but taking enough losses in return to make a pyrrhic victory appear likely. However, the entire attack was a feint to draw the Blood Covenant's attention away from the real threat: Since Pious Ascension's garrison was too large to overwhelm with a ground assault, and the planet was too important to the Blood Covenant war effort to even allow them the possibility of recapturing it, the decision had been taken to utterly destroy the planet. An ONI Prowler launched a NOVA Bomb at the planet and utterly destroyed it, with the entire Blood Covenant fleet getting destroyed in the blast wave. Blood Covenant supply lines were tripled in length, and four Blood Covenant colonies were starved, surrendering three months after the battle. The Blood Covenant leadership, however, once again escaped, this time to Expansive Judgement, where they would remain until the end of the campaign.

Eternal Fealty (June 2556)
Emboldened by their two crushing victories, the alliance was prepared to carry out their threat to attack Eternal Fealty. The Blood Covenant was forced to commit more ships to convoy escort duty, as the UNSC's campaign of Unrestricted Prowler Warfare became more and more agressive and harmful to their ability to supply their dependent colonies. As a result, ships were stripped out Eternal Fealty's defence fleet in order to fill the gaps left by losses to Prowlers. Seeing that the Prowler campaign was doing the Blood Covenant damage in areas that they hadn't foreseen, Admiral Carolyn Webster, Commander, UNSC Prowler Corps, ordered the campaign to be stepped up, to Chairman of the Joint Chiefs of Staff Fleet Admiral Terrence Hood's enthusiastic approval. Eventually, Eternal Fealty's defence fleet had been reduced by half following losses on convoy duty. The allies came to the conclusion that the time to attack had come, and on June 18, 2556, a joint UNSC-Sangheili force entered the system.

Despite numerical parity, the demoralised Blood Covenant fleet was quickly dealt with by the allies, and the six-day ground campaign ended with very few (comparatively) allied losses. In the process, the men of the UNSC Army's 3rd Scottish Infantry Regiment captured a data centre in the planet's capital. After analysing the data, the UNSC learnt that the Blood Covenant was fighting a two-front war, one against them, and another against the New Covenant, and was slowly being pushed back on both fronts. What should have been good news was tempered by the fear that once the New Covenant had dealt with its secessionists, it would turn on the alliance. Fortunately, this proved not to be the case.

Determined Resolve (May-August 2557)
In the weeks and months after the Blood Covenant's moderately successful counterstrike in Operation Hammer, the alliance fought to regain the iniative and offensive momentum. In mid-May 2558, the allies captured the strategic Blood Covenant systems of Determined Resolve, Silent Reverence, and Worshipful Submission, which had been starved into surrender by the Prowler campaign. In the process, a salient - a huge bulge in the front lines - appeared. The Blood Covenant Naval Command saw this as tremendous opportunity to build on their success from Operation Hammer and encircle and destroy or capture the equivalent of three fleets and ten army groups.

Planned by Fleet Master Arboreus, the rising star of the Blood Covenant Navy, the attack, code-named Operation Citadel, was a double-headed encirclement movement that was first aimed at securing Silent Reverence and Worshipful Submission to the "coreward" and "rimward" of Determined Resolve. The massively-outnumbered UNSC and Sangheili pickets in the system were easily overrun by the tremendous Blood Covenant fleets, although the Sangheili were able to do some damage to them simply by fighting to the death. Despite these victories, the depth of planning, and the size of his forces, Arboreus remained unsure of the attack, complaining in a letter to his mate: "Whenever I think of this attack, my stomach turns over. A brilliant man would find a way not to fight a war."

His words were almost prophetic: Knowing the weakness of their position, the UNSC and Sangheili forces at Determined Resolve had built up deep webs of fortifications, both in space and on the surface in a defence plan code-named Operation: KURSK, inspired by those used in Operation: HOT GATES six years previously, and they were equipped with the new Glorious-class Carriers that had caused the Blood Covenant Navy so much grief at Alpha Centauri earlier in the year. Despite their supply lines being dramatically extended after the capture of Silent Reverence and Worshipful Submission, the UNSC Second, Sixteenth, and Thirtieth Fleets held out and fought running battles with the Blood Covenant in the system for over three months before they were reinforced. On the ground, eleven million UNSC and Sangheili soldiers fought twenty million Jiralhanae for control of the planet. Fifteen thousand tanks and eleven thousand aircraft participated in the ground campaign. Finally, on the sixteenth of August, the Sangheili Fleet of Enlightened Benevolence arrived to reinforce the allied forces. Arboreus called off the attack and withdrew his forces, and avoided execution on his return to Expansive Judgement by managing to foist the blame for failure on "junior Fleet Masters and their incompetent execution of war plans." Fortunately for him, these "junior Fleet Masters" were in no position to defend themselves, having been killed during the battle. He did it out of a sense of preservation, knowing that with this defeat, the Blood Covenant would need him more than ever in the coming years. The Blood Covenant leadership recognised this as well, but knew that they could not be seen as weak by not punishing a defeated Admiral. Furthermore, Arboreus was a capable, popular officer and good leader, whom they saw as a person who could overthrow them. They chose to put Arboreus as far away from the capital as possible, and so bundled him and his fleet off to the marginally important Undefeated Glory system until they really needed him. Arboreus didn't get a chance to come home, however, before he was killed at the Battle of Undefeated Glory during Operation: FURY in 2560. The Battle of Determined Resolve is often seen by historians as an arbitrary point after which the Blood Covenant clearly began to lose the war.

The Thorn Wall (September-November 2558)
The UNSC/SAF attack on the Thorn Wall, code-named Operation: BAGRATION, was aimed at finally overturning the Blood Covenant's offensive momentum and forcing them back on to a defensive footing. After their rout at Determined Resolve, the Blood Covenant pulled back to a massively fortified line of planets known as the Thorn Wall, designed so that any besieged planet in the line would be able to hold out until reinforcemnts from the flanks or rear arrived. Furhermore, its sheer size meant that multiple attacks along the line would be impractical and unacceptably costly. Therefore, the alliance was forced to consider a new plan.

The eventual solution was based on that of deep operations, originally a land-based doctrine where corps-sized forces would strike deep into the enemy's rear to deprive his front line of support. Two enormous joint Sangheili-UNSC task forces were assembled in the months after the Battle of Determined Resolve, and in January 2558, set off on a course out off UNSC space, one heading coreward, the other rimward, on round-about routes that would take them around the Thorn Wall and through the poorly-defended coreward and rimward borders of the Blood Covenant, an operation that Blood Covenant Naval Command had never even considered the possibility of. Outnumbering the Blood Covenant defence fleet five-to-one, the two task forces arrived in the Ambient Wonder system, the most heavily-defended of all the rear support bases, and after a two-day battle, destroyed the fleet, orbital infrastructure, and ground-based garrisons and supply dumps. Not even taking the surrender of the survivors, the task forces continued, destroying supply bases in the Balst, Tapach, and Walresh systems, completely cutting out the rear of Combined Operations Group Centre (COG-M). In November, 2558, UNSC and SAF forces moved in on COG-M in three separate systems, destroying the starved and under-equipped force. With their centre compromised, Combined Operations Groups Coreward and Rimward withdrew from the Wall deep into the heart of Blood Covenant space, ceding dozens of vital shipbuilding and industrial systems to the alliance. At this point the alliance reasoned that it was now certain that the Blood Covenant would lose the war, the only question being how long it would take.

Cloistering Expectancy (December 2558)
Cloistering Expectancy is a small world, and was home to a not-insignificant Huragok colony with a population several thousand strong. Though the population was technically neutral, the planet was also on the edge of Blood Covenant territory. Having just regained the initiative from the Blood Covenant, in part through technical superiority, the alliance was not prepared to throw that away by allowing the Blood Covenant access to the finest engineers and technicians in the Galaxy. The Battle of Cloistering Expectancy was conceived as a pre-emptive strike on the world by the Sangheili to deny the Blood Covenant the services of the Huragok. It would also become one of the most controversial acts of the entire war.

Not wanting to antagonise the Huragok into switching sides to the Blood Covenant, the UNSC convinced the Sangheili to allow them to bring along the Huragok defector to the UNSC, Too Much Ballast, in the hope of convincing the colonists to join them without the need for coercion. Unfortunately, mission security was atrocious on the Sangheili's part, which resulted in the Blood Covenant leadership discovering the operation via the Brotherhood of Ruskt. Negotiations with the Huragok via video-link appeared to be going well at first, despite the colonists forbidding Too Much Ballast to land on the planet's surface due to his "treachery", but an hour into the talks, a Blood Covenant fleet arrived in the system with the intention of claiming the colony through force. Outnumbered five-to-one, the small, mostly ceremonial delegation of Sangheili ships had no chance of defeating them, and so were forced to destroy the Huragok colony with a plasma torpedo bombardment. Not wanting to fight a useless battle, the Blood Covenant force withdrew and ceded the now-unnecessary system to the alliance. Unusually, the Sangheili apologised in the strongest possible terms to Too Much Ballast, who withdrew to his quarters for three weeks after the battle (ONI investigators later found that he had destroyed and rebuilt everything in the room twenty-two times). During this time, he communicated with other captive Huragok and organised two hundred of them in an independence movement. On New Year's Eve, 2558, this group stole into the Reyes-McLees Martian Shipyards, rapidly repaired a badly-damaged corvette in the course of an hour, and set a course out off UNSC space, never to be heard from again until 2566, when it was established that they had founded a new Huragok colony, Freedom For All, based on Marxist principles, which to the surprise of Human investigators, actually worked in practice as well as principle, in contrast to Human attempts at setting up a Communist state.

Aftermath
Despite being punctuated by the Blood Covenant's Operation Hammer, which set back the operation by a number of months, Operation: MACARTHUR achieved everything it had been planned to do. In conjunction with the UNSC's campaign of Unrestricted Prowler Warfare, it destroyed hundreds of Blood Covenant ships and captured dozens of critical shipyards, repair bases, and industrial and farming planets. By 2560, the Blood Covenant was in such dire straits that its only response to the alliance was the assassination of Terrence Hood in Operation Tartarus, which ironically only made the situation worse for it as the UNSC public, who had originally been against the war, threw their full support in behind it after the assassination of such a popular political figure. The operation also saw the whittling-down of the Blood Covenant's numerically superior fleets, levelling the playing field for the incredibly lopsided Operation: FURY, which was arguably the most successful UNSC operation of the war.