Operation: DEFIANT STAR

Operation: DEFIANT STAR was a long term campaign aimed at halting the advancing Covenant Remnant. Taking place across two dozen star sectors, it would involve significant manpower and numerous battles and smaller operations, as the UNSC faced the ever increasing threat of a Covenant pincer movement.

Remnant War
The Remnant war had begun six months earlier with an undeclared attack on the colony of Greenwell, which was razed to the ground. Similarly, forces attacked several Sangheili colonies simultaneously. While skirmishes and raids by the Covenant Remnant were common, the Office of Naval Intelligence and Republic Justiciars had little idea of the true scale of the Remnant battle plans, or the forces at their disposal.

Blitzkrieg
When the Covenant launched their assault, they used multiple blitzkrieg spearheads, with colossal fleets punching holes through the UNSC lines and penetrating deeply, leaving token forces to mop up. This tactic had allowed the Covenant to advance far, but were hampered when they encountered Slipspace Scrambler technology, preventing their quick advance and baring their unimpeded advance. The UNSC used this to their advantage, picking them out piece by piece, attempting to blunt their assault. Using this opportunity, the UNSC fortified world after world, meaning every strike turned into a bloody siege instead of a decisive victory. This needed to be changed, and quickly.

Pity's Flank
The Prophet of Pity, a hedonistic and impatient individual, had quickly become bored of the speed of his fleet's conquest. Pity instead took the advice of his top officer, Malernus, and diverged off to the east of the main advance, seeking to flank the bulk of the UNSC's defences. Followed by one of the Remnant's appointed Pirate Princes, Mak Kur, his substantial force looked to be in position to quicken the advance once again. Securing his inner flank was the Prophet of Objection, taking a fleet with him.

Prelude
The Covenant had not just blindly launched an assault on the UNSC, but rather spent months gathering intelligence, finding colony locations, locating UNSC strongholds and fleet positions. The Covenant knew their enemy well, and intended to disrupt him as much as possible. However, their own supply lines were going to be stretched dangerously thin, and this required them to survive by raiding the UNSC's own fuel supplies, as well as civilian fuel.

While Pity was simply engaging in battle to appease his own appetites, Malearnus and Objection took a much more pragmatic approach to the coming battle. They established forward bases and supply caches, and begun sighting targets in preparation for the upcoming conflict.

While the Argon Sector wasn't in the direct brunt of the Covenant's advance, the UNSC had taken measures to begun reinforcing the sector. Recently, they had strengthened the planetary defences of a number of key sectors, as well as building several supply bases to allow the UNSC to maintain a highly mobile warfare style, to assault a larger force. Defence of the 24 star systems in the Argon Sector fell upon Task Force Vengeance, a collection of 3 UNSC Battlegroups, including Battlegroup Axios, Thunderstruck and Sword of Damocles, and a large detachmentfrom the UNSC Engineering Corps. Their closest backup was Task Force Reaver, which consisted of elements of the 11th Fleet held back in reserve, and the 16th Fleet, who were approach the Argon sector to finalize the reinforcement, though would only arrive a week after the initial invasion.

Argon Sector itself was not of vital important as a strategic or tactical target, but by outflanking the bulk of the UNSC defence, the Covenant advance could well advance much deeper into UNSC territory, causing horrendous damage to infrastructure and heavy civilian casualties. The sector was also home to nearly 20 million UEG citizens, whom the UNSC pledged to protect.

First Sighting
The first inclination the UNSC had that the Argon Sector was under threat came at 0433 on April 9th. The UNSC Raven, a Minerva-class Prowler, was performing long-distance reconnaissance, when it intercepted high level communications between Objection and Malearnus. Sending this back to sector command, the local cyber intelligence branch decrypted the message to learn they were moving troops into position to strike across the Argon sector. Relayed to Argon defence command at Guinevere, Raven was tasked with shadowing the oncoming threat and reporting back, while Task Force Vengeance was ordered to move into advance positions against what would otherwise be overwhelming odds. Towing a small number of Orbital Defence Platforms, as well taking a number of ENGCORP mine laying vessels.