Second Battle of Elysia

The Second Battle of Elysia was an engagement during the closing months of the Human-Covenant war that took place on the Outer Colonies planet of Elysia from October 29th to November 10th, 2552. It was the second time during the Human-Covenant war that the Covenant invaded the planet, and was the most devastating.

Background
Following the attempted invasion of Elysia in 2548, the UNSC would begin to militarise Elysia in preparation for a second invasion, which was seen as a certainty due to the Covenant knowing of the planet's existence. The UNSC sponsored evacuations from the planet, moving the majority of the urban population of Elysia to Groombridge-1830. However, by 2552, the lack of a Covenant attack led the UNSC administration to believe the Covenant had no interest in attacking Elysia, or had entirely forgotten about the planet, and permitted those who were forcibly evacuated to return.

Initial Contact
A UNSC listening station in the Elysia system would report several slipspace anomalies to ECOM, which was under Colonel Devin Weeks, at 20:00 hours military time. A Covenant stealth vessel would deploy boarding parties to the station some moments later, taking it out and leaving ECOM in the dark about the coming force.

The Fleet of Divine Purity would exit slipspace and would conceal itself from the UNSC by hiding amongst the system's asteroid field whilst it prepared an organised invasion force. ECOM would deploy a scouting party to the listening station in the morning of October 29, the team would be engaged by Covenant forces upon reaching the listening station and would confirm a Covenant presence in the system to ECOM. The scouting team was able to activate the Cole Protocol before it was wiped out, preventing the Covenant from gaining any useful information from the station.

The Covenant would launch a surprise attack on the planet's defense grid, with a sizable amount of ships, 11, assaulting the five Orbital Defense Platforms active above the planet. Losing three vessels before being able to punch through the ODPs by boarding and destroying the UNSC Beach, the Covenant was able to get transport vessels to the surface and initiate the invasion.

Fall of the Defense Grid
With the destruction of the UNSC Beach, the Covenant were able to evade the surviving ODPs and move towards the surface. The UNSC would have eventually organised a proper response to the attack some time later, sending forces to reinforce the four remaining ODPs to repel potential boarders, and positioning the defense fleet to cover the gap created by the destruction of the Beach. The Covenant would begin to board the remaining ODPs at this time. Not knowing of the true size of the Covenant force in the System, ECOM would believe that defeating the attackers in orbit would result in a victory. Going through with a plan drafted by Admiral Mayer, the UNSC would engage the Covenant forces in orbit and would successfully bait a number of capital ships into the kill-box of the remaining ODPs. However, this would prove to be the UNSC's greatest mistake during the battle, as the fleet would have weakened itself attempting to defeat the attacking force, leaving them essentially defenseless when the remainder of the Fleet of Divine Purity began to attack the Defense Grid. ECOM would lose the remaining ODPs within an hour, and the remaining naval elements would be brought to the surface to oversee evacuations.

Surface Combat
From October 30 to November 3, the UNSC and Covenant would clash on the surface of Elysia. The Covenant would glass several regions of the planet, which included multiple cities, resulting in the deaths of hundreds of thousands of civilians. On the third of November, the Great Schism occurred, and the UNSC gained the upper hand in the fighting as the Covenant descended into infighting.

Great Schism and UNSC Counterattacks
On the 4th of November, the former commander of the Fleet of Divine Purity would form the Lights of Purity, and would begin to engage Covenant-loyal forces, Separatists and the UNSC indiscriminately. The UNSC would strike a deal with Separatists that were not aligned with the Lights of Purity, and they'd begin to assist eachother in the fighting on Elysia's surface. The UNSC launched a counterattack on the 5th of November with the assistance from a large number of Separatist forces, recapturing several regions of the planet by November 7th and driving the Covenant off the surface by the 8th.

UNSC Victory
The UNSC and Separatists would, following their victory on the surface of Elysia, gain the upper hand in the fighting in orbit, with remaining UNSC vessels joining the battle and assisting the Separatists in engaging the Covenant. The Lights of Purity would retreat from the system prior to these attacks, and would not participate in the battle. By the 10th of November, the UNSC and Separatists had handed a total victory to the Covenant, with survivors retreating from the system.

Aftermath
Following the Second Battle of Elysia, large sections of the planet were left desolate and devastated by Covenant attacks, several regions having been outright glassed. The battle, despite being overall shorter than the first battle, was twice as devastating with significantly more civilian casualties.

The Separatists that aligned with the UNSC during the battle would leave the system to return to Sangheilios, with many being decorated by the UNSC and given pardons for perceived crimes against Humanity.