OPERATION: BLACK CARD

"It was breathtaking.." - Rose-788 describing the structure during debriefing.OPERATION: BLACK CARD was an engagement that took place in the Forerunner Structure beneath the planet of Society that took place over four days from the 20th of November to the 24th. The relatively small UNSC force managed to escape the underground and destroy the structure, preventing the Covenant from utilizing it and wiping out all forces within the structure. Due to the Covenant being pre-occupied fighting the Sentinels, who were impartial and non-hostile to the Human presence, UNSC forces in the structure only suffered minimal casualties. The operation marks one of the only times where Insurrectionists directly assist the UNSC against other Insurrectionists.
== Background ==
On the 17th of November, 2548, the UNSC Ivory Coast was part of a small force tasked with searching for a specific structure on the surface of the planet Society, which had been glassed a decade prior. ONI had drafted OPERATION: BLACK CARD after discovering that the Covenant were attempting to activate the facility beneath Society to use against Humanity.
Due to a leak within ONI, the remnants of the Society Insurrection, which had survived due to the many cave systems on the planet sheltering them from the glassing, would have been informed by Kayode Adetola of the Operation's true nature, rather than the cover story of a planetary search-and-rescue. The Insurrection had knowledge of the Covenant presence in the structure as the Society Insurrection had been monitoring Covenant troop movements for years previously, and therefore knew of the threat the Covenant would pose. Insurrectionist forces under Michael Christiansson entered the structure on the 19th of November to set up an ambush for the coming UNSC forces, and to capture the Facility for himself.
On the 20th of November, Fireteam India, James Coleman and Rose-788 entered the Forerunner structure. Shortly after entering, they were confronted by an AI, which referred to itself as Cassandra, and were brought to the structure's control room via the teleportation grid. 
The Covenant had been in the structure for some years at this point, with a small number of scribes and a modest guard force who had been attempting to access the structure, with very little process. By the 20th of November, they had finally managed to discover the location of the control room within the gigantic structure, and were travelling through the large tunnels towards it.
== Operation ==
=== November 20th ===
"Those who wish to use this facility for their own gain are well on their way to achieving their goal." - Cassandra to the members of Fireteam India.Upon reaching the control room, Cassandra would inform James Coleman and Rose-788 that they were in grave danger, and would teleport Fireteam India to the structure's library in order to have them retrieve a specific index among the collection. Once Fireteam India was in the library, Cassandra would give them a personal briefing, informing them all that the Covenant were in the structure and were likely to reach the library. Cassandra then told both the Fireteam and James Coleman that the Covenant had obstructed the AI's control over the structure's sentinels two months prior, and that the index India had been send to retrieve was needed to activate them, though it would not give the AI control over them.
Fireteam India was ambushed in the library by Kayode Adetola, who surrounded them and forced them to negotiate. Kayode told the fireteam that they had a common enemy, and that the Covenant posed a greater threat to the UNSC than Kayode did. Cassandra would talk to the two groups, and would then teleport them to the control room, where Kayode also talked with James Coleman and Rose-788. Kayode agreed to ally with James Coleman and his forces temporarily to stop the Covenant from gaining control over the facility.
After the alliance was formed, Kayode's men were teleported to the control room, Rose-788 would use the index to activate the facility's sentinels. Cassandra reaffirmed that they had no control over them, only that they were now able to activate and de-activate them at will. With the activation of the Sentinels, the Covenant began to be engaged across the facility, which lit up the battlenet and caused chaos. Michael Christiansson's forces entered the library at this point in time.
=== November 21st ===
After they had gained some rest in the warrior-servant dwellings in the facility, the allied forces reconvened in the control room, where Cassandra urgently informed them that the Covenant had attacked Christiansson's scouts in the facility, and was using the captured humans to unlock the tunnels on the path to the control room. Seeing as the situation was dire, Cassandra was forced to come to terms with the fact that the facility needed to be destroyed. Cassandra teleported Rose-788 to a surface entrance where she would obtain a HAVOK Nuclear Device. Cassandra then teleported Rose-788 back to the control room and requested she pulled Cassandra from the system to prevent her from falling into Covenant hands. Cassandra, using a small fragment of herself she kept in the system, would teleport them back to the warrior-servant dwellings, and would destroy the fragment left behind. From there, James Coleman and allies were forced to find the facility's core in order to destroy it. Guided by Cassandra, they'd ambush a Covenant platoon in the tunnels and would commandeer three Type-29 Shadows. From there, the group would spend the rest of the day travelling. 
=== November 22nd ===
The Covenant breached into the control room in the early hours of November 22nd, and would begin attempts to gain control over the facility, with little initial success. Rose-788 would leave the group aboard a Type-32 Ghost in order to plant the weapon. Kayode Adetola followed her in another Ghost, unknown to her. Once she had reached the tunnel system leading to the core, Rose noticed and confronted Kayode. Kayode would label her an ONI spook and use it as justification to go with her to the core - to ensure she planted the bomb. Rose-788 did not object, and allowed him to go with her.
Michael Christiansson's forces would notice that they were trapped in the structure, and would leave the library. They aimed to reach the core and override the lockdown by disabling the systems that controlled the lockdown.
=== November 23rd ===
Rose-788 and Kayode Adetola would have rested for the night, and reached the core early in the morning. Rose planted the bomb, and would wait for Coleman, Fireteam India and Allies to reach the core. By late afternoon, Christiansson's forces arrived at the core, and entered, a firefight beginning between the Insurrectionists and Rose-788, with Kayode providing ranged support. The Insurrectionists eventually were forced to end their assault on her position, and instead began moving towards the core's control room. Fireteam India arrived with Kayode's Insurrectionists, and they successfully drove Christiansson's forces out of the core before they could go through with their plan. The HAVOK was set to detonate in exactly 24 hours to remove the risk of it being disabled. They'd then leave the core and began moving towards the closest exit.
=== November 24th ===
The convoy was ambushed by the Covenant as it approached the exit, with six Insurrectionists being killed before Sentinels began to arrive in mass numbers and swarmed the Covenant. Rose-788 was severely wounded in the ambush, having drawn the majority of the Covenant's fire, and Fireteam India's combat medic began to tend to her wounds. They would reach the exit an hour before detonation. Cassandra was inserted into the local system via an access port where she opened the entrance. The Covenant, who were still engaging the sentinels, caught wind of this and immediately moved a large amount of assets into the area via Phantoms, forcing the humans into a confrontation. Kayode Adetola and his men would stay behind to allow the UNSC forces to escape. The entrance was closed after they had exited, trapping everyone else inside. Cassandra was pulled from the local system from the exterior access point, and the UNSC Ivory Coast deployed pelican transports for the UNSC forces, which quickly transported them to the ship and had the wounded receive urgent medical attention. Cassandra was housed in an AI containment unit aboard the Ivory Coast until the vessel arrived on Earth.
== Aftermath ==
Following the Operation, Kayode Adetola was declared dead. Being dead, Adetola did not have any standing criminal charges nor was he still one of the most wanted people in UNSC space. Unbeknownst to ONI and the UNSC, Adetola and his men only stayed behind to give off the illusion of their death, and actually had used a fragment of Cassandra to leave the facility aboard a captured Phantom. Adetola immediately went to the Inner Colonies and had a long vacation, making the most of the time he had until ONI realised he wasn't dead.
Cassandra was handed over to ONI, which transported her to Solitude, a ONI black-projects research facility on Luna. Cassandra was studied extensively, and ONI looked for a way to use the AI as a weapon against the Covenant. Research would be interrupted when Kayode Adetola "rescued" the AI during his raid on Solitude.