Battle of Grannus

The Battle of Grannus was an engagement between the United Nations Space Command (UNSC) and Covenant during the Human-Covenant War. The battle took place on and around the colony of Grannus in the Zeta Galvana System, from July 11th to July 29th 2546. The battle would see heavy casualties on both sides both due to the the inhospitable conditions of the world and the savage ground battle taking place. Despite the intensity of the battle the UNSC would manage to secure a pyrrhic victory, losing their entire naval force, suffering heavy casualties on the ground and retaining half of the vital mining stations on the colony.
==Prelude==
With the outbreak of the Human-Covenant War in 2525 and the entire UNSC being placed on alert in November, Major General Theodore Hannely of the UNSC 173rd Mechanized Regiment was forced to violate the terms of the Hannely-Tensdale agreement which resulted in the reallocation of the output of all mines to UNSC facilities both on and off world, despite push-back from the Governor Tensdale and the workers. However this opposition was soon silenced, not by force, but rather by the sheer influx of damaged equipment and injured personnel as well as refugees from other worlds, often arriving in such numbers that the local healthcare facilities were getting overwhelmed, even with support of the UNSC. By 2542 the influx of the injured arriving seemed to thin, much to the brief relief of the inhabitants of Grannus, although the actual meaning of this was far more worrying and saw the bolstering of the planetary defence fleet (originally only a couple of Charon-class frigates) to three Paris-class heavy frigates, three Halberd-class destroyers, two Halcyon-class light cruisers and an Orion-class assault carrier. Furthermore the bunkers once used to shelter the population from ash storms were appropriated to be used as fallout bunkers. By 2546 the situation had evolved into a waiting game as whatever personnel could be evacuated, were evacuated but the miners, farmers and even Governor Tensdale herself refused to be evacuated from their home. 
The first signs of a Covenant attack arose in the early hours of June 9th, 2546, as ONI Listening Stations Alpha through Gamma all went dark without any warning or reason. At 8am UTC, as the sun rose on Raymond Station, the Zeifer Communications Relay encountered sufficient interference with the Deep Space Communications Satellite before losing all connection, initially this was not taken too seriously as the sun had shown a spike in the frequency of solar flares and could have been the reason for the loss of communications across the planet. In an effort to ensure this was the case, a platoon from SPECWAR Group SEVENs 88th Special Warfare Battalion was deployed to the seismic activity monitoring stations around the Raduga super-volcano. 
==The Battle==
===Initial Space Engagements===
At 9:57am UTC, sensors aboard the cruiser UNSC Endless Summer picked up a cacophony of slipspace readings several hundred kilometers outside the defensive sphere of the fleet; In response, all ships were placed on alert with the frigate UNSC Roosevelt sent to confirm the ruptures. Upon closing the distance the Roosevelt came under heavy fire from cloaked SDV-class heavy corvettes. The alarm was sounded across all channels and the fleet moved to engage the still arriving Covenant fleet while the message was relayed to the surface. 
At 10:29am UTC, after forming up with the rest of the fleet, the carrier UNSC Highlanders Blade along with cruisers UNSC Endless Summer, Easy Goer and destroyers UNSC Zenith and Jacinto moved to intercept the two corvettes which were now accompanied by a trio of CRS-class light cruisers. Meanwhile, the destroyer UNSC Gustav under Captain Wilson Invar, along with frigates UNSC Roma and Zulfiqar moved to cut-off any attempts made towards the surface. With all ships in range, Rear Admiral Joanne Darby opened fire on the fleet, causing three of the ships to divert course to meet her forces with the other two accelerating towards the surface. 
Fleet Master Yul 'Haramatanee had—up to this point—been observing his fleet, preferring to observe the battle from a distance. However, seeing a much larger fleet than he had anticipated necessitated a change in plan. He ordered the light cruisers Sharpened Blessing and Endless Devotion to make for the surface and target the meager human settlement on the world and split their fleet; Simultaneously, the corvettes Prophets Will, Believers Shield and the light cruiser Journey's Song would move to distract the fleet and allow him to attack them from behind. Mobilizing all three battlecruisers, including his own, he ordered the ships engaged with the human fleet to link up with the two waiting battlecruisers, Echoing Pslam and Rapturous Prayer, at the planets perimeter to draw the human fleet away from the world. Meanwhile, he ordered his battlecruiser, Blightless Faith, to conduct a pinpoint slipspace jump near the human fleet, allowing him to strike at the human ships with his own. 
===Securing Seismospy Station===
By the time the Grannus Defense Fleet had engaged the Covenant Fleet, 2nd Platoon from 'C' Company of the 88th Special Warfare Regiment 'Sabatons', under Lieutenant Fabienne Montoya, was already en-route to the Seismospy seismic monitoring station. When the alarm was raised that the Covenant were confirmed to have found the planet, their objective was rerouted from a scouting operation to securing or destroying the monitoring station as it contained sensitive meteorological data including coordinates to several inner colonies, as per the Cole Protocol. Despite being under equipped, only four Warthogs, two Mastodons and a single Leopard for fire support; Lieutenant Montoya carried forward with her mission, advising any available units within their vicinity to lend support. By 11:03am UTC, 2nd Platoon was within view of the monitoring station, and had received word that two UNSC frigates were in pursuit of two Covenant light cruisers and were set to pass over them. 
By the time the station was being secured, Lieutenant Montoya received word from the UNSC Zulfiqar that the light cruisers had broken atmosphere and were deploying troops enmasse. In response, after they finished securing the facility, Montoya directed her troops to dig in, the Leopard being dug in facing the north-west and the Mastodon being dug in facing south-east and the road from which they came; Meanwhile one of the Warthogs would be escorting the station staff, in their vehicles, back to Raymond Station, while the other would act as support to the dug in vehicles as the noise of the battle above them intensified.
===Interception of the Strike Force===
While in low orbit, the Sharpened Blessing and Endless Devotion had been intercepted by Captain Wilson Invar's interception group, rather than engage the ships directly though, they kept their heading for the surface, using their pulse lasers to ward off the pursuing ships, while they deployed mass amounts of drop pods and drop ships, to only minor effect. As they descended, the Zulfiqar and Roma had managed to land multiple hits, both with missiles and a single MAC, on the light cruisers, forcing them to conduct evasive maneuvers, leading them in the direction of the troops of 2nd Platoon. Despite their best efforts however, they could not bring down the cruisers but Roma did manage to disable one of the engines of the Sharpened Blessing, leading to mass deployment of the externally mounted transports. 
===Holdout at Raduga super-volcano===
The explosion from the Sharpened Blessing was clearly audible to the troops on the ground, allowing them to spot the ships high above them and the transports which were heading towards them. Counting at least six Liches and their vehicles, Lieutenant Montoya ordered her troops to set up defenses and later contacted the Zulfiqar to provide danger close fire support as they flew past, hoping it'd be enough to allow her men to hold out. However, minutes passed with no response from the Zulfiqar and the transports were now landing troops to the west; Montoya was about to order a complete destruction of the station, but was stopped short as a barrage of cannon fire and archers impacted the landing areas, taking out and damaging several transports and whatever troops had landed, forcing the Covenant to hold position as the ships soared past the station and towards Raymond Station.
===Ongoing Space Engagements===
Over the course of the Skirmish, the situation seemed dire for the units in orbit; Rear Admiral Darby had succeeded in forcing the corvettes from the planet and had even destroyed the light cruiser Journey's Song while the other two dove towards the planet, but the appearance of the two battlecruisers Echoing Psalm and Rapturous Prayer had halted any further advance of her forces. Instead she ordered her ships to fall back into a defensive perimeter above Raymond Station, directing the her carrier and the cruisers to deploy all their fighters. At 12pm UTC however, there was a sudden slipspace rupture behind her forces, and the subsequent barrage from the Blightless Faith. The Jacinto was crippled by heavy damage while the Easy Goer had its engines knocked out, leaving the Endless Summer and Zenith to engage the ship while the Highlanders Blade came around to engage. 
Having dropped out of slipspace, the Blightless Faith routed all power to its weapons and opened fire on the human ships, crippling two of them as two others moved to attack it. As power returned to its engines, the Fleet Master immediately conducted maneuvers to avoid his ship getting hit before the shields were raised, causing the MAC rounds from the Zenith to miss and cannon fire from the Endless Summer to go wide. This resulted in both ships launching a combined mass missile barrage, the volume of which allowed several to bypass the pulse lasers and impact the Blightless Faith, destroying its hangars before the shields could be raised. In response, Yul ordered the targeting of their flagship with his torpedoes while his plasma cannons targeted the MAC barrels of the other two ships, hoping to cripple them and allow his other ships to take them out. 
At 12:08pm UTC, several plasma torpedos struck the side of the Highlanders Blade, dealing heavy damage, crippling hangars, sensors and compromising the assembly lines as well as other functions. The Zenith meanwhile had been all but destroyed as the plasma cannons struck its MAC while firing, causing the fore end of the ship to be blow-off and causing major power outages; the Endless Summer however, managed to use its emergency thrusters to evade its MAC getting damaged, the plasma cannons instead striking its hull and sensor array, and turned once again to engage the battlecruiser, firing MACs, missiles and all. This, along with combined fire from fighters and the remaining guns on the Zenith and Highlanders Blade, allowed them to breach the shields, albeit with little ammo left to destroy the ship, allowing the Fleet Master to respond. 
Having been caught off guard by the loss of his shields, the Fleet Master authorized his other ships to advance to relieve pressure; In the mean time, he routed more power to his weapons and struck back at all three ships, cutting a gash across the Endless Summer with a plasma lance, forcing it to pull away, and further hammering the Highlanders Blade, taking out weapon emplacements and its secondary engines. However, unknown to the Fleet Master was the rapidly approaching UNSC Gustav, which opened fire as soon as it was within range, disabling the engines of the Blightless Faith with its MAC, causing it to be uncontrollably pulled down towards Grannus as it fired wildly at the Gustav damaging its point defense guns and sensor arrays. Though the victory was short lived, as the battered fleet now faced a trio of due of battlecruisers and heavy corvettes; Despite their damaged state, Rear Admiral Darby ordered her ships into a defensive perimeter above Raymond Station at 1pm UTC. Oddly, the Covenant didn't immediately advance, allowing the UNSC fleet to regain some composure and effect repairs. 
At 3:10pm UTC the Highlanders Blade received word from the Seismospy Station that the sun seemed to be set to release an excessively large solar flare which could potentially damage their systems and recommended an evacuation. However, rather than evacuate, Rear Admiral Darby ordered a time estimation for the flare, as the fleets sensors had been crippled, and ordered a full assault on the Covenant fleet. At 3:22pm UTC, the star Grannus orbited, released an abnormally large solar flare, interrupting communications across Grannus and, most importantly, nearly disabling the shielding of the Covenant fleet. Taking advantage of the situation and their close range, Rear Admiral Darby ordered all ships to open fire in order to disable what was left of their shields and damage their vessels with what little ammo they had left. Despite the unexpected attack, the Covenant fleet quickly responded to the closing human warships with barrages of cannon fire, but noticed they didn't stop, even after heavy damage. At 4pm UTC, Rear Admiral Joanne Darby enacted the Cole Protocol with the launching and internal detonations of several Shiva-class nuclear weapons, destroying all UNSC and Covenant ships above Grannus.
===Raymond Station Landings===
At 12:24pm UTC, minutes after providing fire support, UNSC Zulfiqar refocused its weapons, along with UNSC Roma, on the two light cruisers ahead of them, with the former making sure to target the now slowing Sharpened Blessing as they neared Raymond Station. However, with their current altitude and range, neither frigate could safely utilize their MACs, forcing them to use NCGs and missiles; despite this, the Roma managed to breach the shields of the Endless Faith, forcing it once again to make evasive maneuvers, but unlike before, the Sharpened Blessing did not follow, and instead maintained a heading towards Raymond Station, splitting the chase in two. At 1pm UTC, now alone and within visual range of the station, the Sharpened Blessing began to fire its weapons wildly, striking vehicles on the roads below and buildings on the outskirts of the city; fearing a glassing attempt, and to avoid fire from the Sharpened Blessing, the Zulfiqar dropped altitude and fired its MAC and remaining missiles into the bottom of the Sharpened Blessing destroying its last engine, reactor and numerous other systems but also causing it to crash into the outskirts of Raymond Station, destroying several buildings by the crash and scarring the surface with the leaking reactor.
While the Zulfiqar engaged the Sharpened Blessing, the Roma broke off to engage the Endless Faith, forcing the light cruiser further away from Raymond Station and allowing Roma to utilize her weapons freely. As a result of this, and after having broken the shields of the Endless Faith, Roma was able to make quick work of the light cruiser with its MAC and missiles, tearing the light cruiser apart but not before it was able to cut several gashes into the Roma with its pulse lasers. As the Endless Faith crashed, the Roma made to link up with the Zulfiqar and search and rescue for those around the crash site of the Sharpened Blessing. At 2:47pm UTC however, unbeknownst to either of the frigates or the troops stationed in Raymond Station, was that the crippled Blightless Faith had survived its its unshielded entry into Grannus and so too had Fleet Master Yul' Harmatanee. 
At 3:02pm UTC, the Blightless Faith and numerous dropships were detected on the Roma's sensors causing both it and the Zulfiqar to move and engage the cruiser, but before they could, the Blightless Faith opened fire with all its weapons on both frigates and Raymond Station while simultaneously deploying troops enmasse. Both the Roma and Zulfiqar sustained heavy damage and were forced to crash land several kilometers from Raymond Station, leaving the station defenseless as the cruiser neared, culminating with a controlled crash landing of the cruiser into the heart of Raymond Station, killing thousands with the initial crash landing as well as wiping out the 129th and 114th Infantry Battalions. 
===Breakout from Seismospy Station===
At 3:10pm UTC, tech specialists of 2nd Platoon had managed to bring the station online which immediately began to sound alarms for abnormally large solar activity, with automated messages being sent to Raymond Station and Everest Base; Fearing the solar flare would disable their fleet, Lieutenant Montoya ordered the information be transmitted to the flagship of the fleet. While they attempted to bring the long range radio back online, 2nd Platoon came under heavy fire from a massed charge of Covenant infantry, being spearheaded by Grunts and Jackals. They responded with sustained machine gun fire and grenades, cutting down the hordes, but also distracting them from the Elites and Hunters who had circled round the station, using the terrain as cover, and opened fire on the moving Warthog which it narrowly avoided. Rather than risk it getting destroyed, the Leopard crew drove out of their position and charged one arm of the flank while the other was suppressed by infantry; the Leopard narrowly avoided fire from the Hunters and made quick work of them with its main gun before cutting down the Elites with its machine guns. Despite repelling one arm, the attackers seemed to double down on the other, nearly overwhelming the troopers, which caused the Mastodon to also leave its position and provide mobile cover for the troopers who now began to push forward. Taking advantage of the situation, the Leopard and Warthog charged a separate dune, cresting it before opening fire on the few remaining covenant assembled behind it, the Mastodon and troopers pushing in moments later. 
Having broken through the Covenant surrounding the station, the troops and vehicles of 2nd Platoon returned to their positions, only to be halted a series of incredibly bright flashes in the sky above them. In the time of the engagement, Rear Admiral Darby had initiated the Cole Protocol and she along with her and the Covenant fleet had been destroyed. Now without communications and certainly without orbital support, Lieutenant Montoya ordered the destruction of backup servers in the station, terminating all data pertaining to colonies aside from Grannus. Furthermore, rather than risk the station being captured later, Lieutenant Montoya instructed her troops to destroy the station, primarily by filling the reactor room with Fusion Coils and placing a demolition charge on the pile to allow her men to fall back to a safe distance.
By 5:30pm UTC, with the core room brimmed with explosives and fusion coils, the troops of 2nd Platoon disengaged from the station to a rally point four kilometers away before detonating the charges and advancing further towards Raymond Station. By the time they were within visual range of Raymond Station, 2nd Platoon had come across the crash site of the UNSC Roma; after scoping it out, Lieutenant Montoya and a squad advanced in the Mastodon to investigate. Arriving at the site, which was somewhat intact, they found several injured personnel but couldn't risk moving them under a full communications blackout; therefore, after gathering and patching up who they could, 2nd Platoon raided the hangar, finding another pair of serviceable Warthogs for her men. With few other choices, Montoya allowed her troop to rest in the wreck of the ship, while she and another squad scouted ahead. 
Advancing further brought the squad to a hill from which they could see the devastation Raymond Station suffered, the husks of two destroyed Covenant ships rested on the surface, the larger one in the heart of the station, but what was more eyecatching was the numerous Covenant troops and vehicles teaming around the crash site. With no way to contact Everest Base or take on such a large force, Montoya and her squad fell back to the crash site of the Roma where she formulated a plan to help the troops, if there were any left, at Everest Base, namely by acting as raiders; striking the Covenant while they were distracted and taking out their supplies. 
===Siege of Everest Base===
The first activity in Everest Base began at 8:15am UTC, prior to the battle, with the deployment of the 2nd Platoon of 'C' Company of the 88th Special Warfare Battalion 'Sabatons', being deployed to the Seismospy Seismic Monitoring Station to confirm that the losses of system wide communications was due to the solar flares; in the event this was not the case, the station was to be evacuated and then destroyed in accordance with the Cole Protocol. But with the alarms sounded at 10:10am UTC,the worst case had come to pass and the 129th Infantry and 92nd Infantry Battalions were deployed to Raymond Station to begin fortifying positions as well as helping local authorities with evacuating civilians to the glassing bunkers. Meanwhile, the 31st Cavalry Battalion and the 114th Infantry Battalion took up defensive positions within Everest Base, with reconnaissance elements of the 31st being used to scout out the area around the base and Raymond Station. At 11:03am UTC, the base received word that the UNSC Roma and Zulfiqar were engaging two CRS-class light cruisers headed for the surface, prompting deployment of the bases missile batteries and gun emplacements; However, these would prove unnecessary as the Zulfiqar brought down one of the cruisers while the Roma drove off the latter. As a result, recon elements of the 31st were retasked to survey the crash site and evaluate if there was any continued threat. 
At 3:04pm UTC, Everest Base received word from the Roma of the inbound Blightless Faith before losing contact, one again placing the base defenses on alert; However, the subsequent barrages and crash of the Blightless Faith had seen a full breakdown of communications with units inside Raymond Station. Subsequent recon reports highlighted mass Covenant troops 'cleansing' the station, eliminating troopers and civilians in large quantities. Despite the news, Brigadier General Hannely held his composure and pulled back his forces, digging them into entrenched positions and setting up a network of defensive rings around the base perimeter, interspersed with mines, barriers and 'murder holes'. Furthermore, he had the two battalions of SPECWAR Group SEVEN, originally there to simply be repaired and rearmed, prepare to be deployed; In particular, he ensured the two squads of Ballista's be combat ready within the next two hours, to give him units which could be deployed on the surface with no need of resupply.
At 3:58pm UTC, Everest Base received word of Rear Admiral Darby enacting the Cole Protocol, the solar flare and numerous nuclear explosions being visible in the sky above Grannus, the former of which knocked out all long range comms in the base and cutting them off from deployed recon elements. Following the loss of comms, Brigadier General Hannely instructed another recon unit of the 31st, this time with more M627 Leopard's, to be deployed to the east of the base, allowing them to put distance between themselves and the base and set up short range comms stations. However, these comms stations were quickly abandoned as the departing units were fired upon by a large advancing Covenant force under Field Master Esan' Tulamee, forcing them to retreat back into the base after a trio of Warthogs were destroyed. 
As they closed the gap, the bases defenses opened up, cutting a swathe across the advancing Covenant and forcing them into the heavily trapped ditches and incurring further casualties, causing the attack to halt. Though the real reason for the halt was the Field Master bringing up his own heavy artillery in the form of two batteries of Wraiths, which made quick work of the human defensive turrets and soon turned on the few above ground structures they could see, causing mass panic below ground as hallways and rooms were breached by the constant barrage. With few choices in how they could respond, Brigadier General Hannely ordered a retreat from forward, non-essential sections of the base. Rather than advance his spent troops, Field Master Esan' Tulamee instead ordered the construction of numerous walls and siegeworks around the base, allowing his troops shelter from the harsh climate of the planet and time to consolidate his forces to mount a proper assault on the human base. Similarly, Brigadier General Hannely elected to hold off on any further advances and instead had engineering units work on tunneling new pathways to the east, to allow him to deploy his own armored units; forcing both forces into a temporary stalemate.
Over the next week, from 11th June till 18th June, there were only minor skirmishes; Covenant advances were halted by the few hidden UNSC defensive positions and numerous traps, while the UNSC breakout attempts were repelled with heavy losses, the bottlenecks caused by the surface exits making ideal places to stop any attempts at a breakout. Meanwhile, there had been some sufficient progress in tunneling to the east, with a tunnel capable of allowing vehicles through being projected over the next 4 days. A much larger concern, however, was the advances of cloaked elites into the abandoned sections of the base, necessitating their collapse and the loss of several food stores when dozens had already died of injuries and dehydration. Despite the bleak situation, and unknown to the forces inside Everest Base, the 2nd Platoon, now with support from the survivors of the Roma and the recon elements deployed to Raymond Station, had been conducting numerous raids on the Covenant forces. Usually using their Leopard to engage supply vehicles and transports from excessive ranges while the Warthogs would surprise from the complete opposite direction, gunning down the distracted defenders. 
While the raids had played a large part in halting a further advance, they did not address the issue of the ever expanding line of Covenant siegeworks which now encircled majority of the base; while initially just dug in Covenant troops, they had been expanded by the setting up of bunkers and pillboxes, using sections of their crashed ship. Due to this, the armored units in Everest Base had to improvise in the event of a full assault; as well as the main tunnel being built to the east, a series of shorter tunnels ending in rooms were also built to the north and south, allowing artillery to fire with relative cover, though their luck in moving out before Covenant counter battery fire impacts seemed to be wearing thin with 4 guns out of 9 being damaged or knocked out. 
However, on June 20th at 1:27pm UTC, sensors of Everest Base were able to detect the approach of the 2nd Platoon raiding party; Taking advantage of the situation, Hannely ordered that the vehicles open fire in conjuncture with the raiders. While this took place, part of the Leopards of the 31st, as well as part of the M850 Grizzlies of the 88th Armored Battalion, would breakout into surface positions and attempt to break the siege of the base. At 1:32pm UTC, six Grizzlies and ten Leopards broke out onto the surface with the grizzly's leading the charge, but were immediately met with fire from Covenant positions; with the grizzlies drawing fire, the Leopards began their push, four of them heading east to reach a safe distance before linking up with 2nd Platoon, while the other six took up positions along with the grizzlies. The engagement lasted for hours, the Covenant forces lacking the fire power to knock out the tanks, but the tanks couldn't risk an advance against their positions, lest they are ambushed from below or the rear; the Leopards had meanwhile taken significant damage, their wheels damaged by the constant barrage, effectively turning them into lightly armored pillboxes. 
While the human forces believed they were on the verge of a breakout, Field Master Tulamee had other plans; he had been pulling back his forces from the human positions and had been setting up a second ring of defensive structures, a short distance behind the old ones, and leaving the old ones surrounded by numerous plasma mines beneath the sand. With the fortifications on their last legs, he ordered a full retreat to bait the human armor, which they seemed to take; the tanks advanced under the cover of the other vehicles and were soon tearing through the remnants of the fortifications, prompting the Field Master to detonate the charges, crippling most of them before once again opening up on them with barrages of Wraith fire, the combined fire causing two to be destroyed and the others locked into their positions. Despite their continued resistance, their guns soon went silent, the crews within scuttling their tanks and themselves rather than letting them be captured by the Covenant. 
The failure of the breakout caused great concern in what was left of the commanding staff of Everest Base, Brigadier General Hannely in particular had been sealed within the planning room for over a day, trying to think of a way out of their situation; but he was interrupted by news that the two squads of Ballistas had reached operational capacity, while their reputation spoke highly of their accomplishments, he doubted even they could breakout from the bottle necks they had become trapped in. The next week would be the hardest yet, as the Raduga super-volcano now came to life, spewing massive clouds of ash, blinding both the UNSC and Covenant forces, leading to yet another deadlock between the forces, neither risking an attack under such conditions. But it was these conditions which allowed Hannely and his staff to finally think of an idea. The only forces capable of setting foot outside the base under such conditions were the armored vehicles, and with the eastern tunnel finally open it seemed like the ideal time to try breaking the line once again, but this time with a much larger force and including the Ballistas. 
===Operation GALILEO===
At 6:34pm UTC on June 29th, during a lull in the ash storm, sensors on Everest Base picked up large amounts of Covenant forces massing near the previous defensive positions, raising the alarm for an imminent attack and prompting a short window of fire from the artillery and an assembly of Leopards within the eastern tunnel, while the Grizzlies utilized the existing exits due to their slow speed. Unlike their vehicle counterparts, the Ballistas would be advancing through the sections of the base near the surface which had been breached by the Wraith bombardment. At 7:02pm UTC, with the raiders being detected on a heading to the Covenant forces, Operation GALILEO was officially started, starting with an artillery barrage to both shock and further blind the Covenant and allow the Grizzlies to exit with relative cover. Prior to the attack, at 7:00pm UTC, twelve Leopards of the 31st Cavalry Battalions Armored Squadron and fourteen of the 88th Special Warfare Battalions Armored Squadron advanced at speed through the eastern tunnel, escaping Covenant detection, and taking up positions behind dunes on the flanks of the base.
With the order given, eight Grizzlies advanced under the cover of artillery fire and into forward positions; along with them, the Leopards began to advance into supportive fire positions on the flanks of the grizzlies. While the armor advanced and took the brunt of the fire, Ballista squads under Windsor and Corvus began their advance, utilizing their recoilless rifles as mobile mortars to cover their advance and further break down the old Covenant lines. By 7:12pm UTC, the old Covenant lines had been all but destroyed which also resulted in several explosions from the detonations of mines and other improvised explosives; taking advantage of the clearing, the Grizzlies pushed their line, as did the Leopards, but the Ballistas continued to hold until the order to advance was given. 
Knowing the humans wouldn't risk a brash assault like before, Field Master Tulameee had hunkered down his troops, staying out of view as best they could while his main force waited for a gap in the storm to mount a final assault and break the humans; The prolonged artillery barrage, while unexpected, had become something of a common place over the weeks, what was more unexpected was the fact that the artillery seemed to be targeting the old lines, suggesting the humans may try to advance. Rather than launch a preemptive strike, the Field Master instead chose to continue holding the line and ambush the humans with a counterattack as they neared their lines, using his main force. At 7:15pm, with the focus of his forces towards the human armor, the raiders opened up, firing from long range with their tank as well as distracting and killing his forces with their faster vehicles. 
At 7:23pm UTC, upon spotting a large heat signature resembling an explosion at the Covenant lines, all units received orders to advance towards the covenant lines and open fire; The Grizzlies lead the charge and drew much of the fire as before, but unlike last time, they stormed through the old covenant lines with the Ballistas at their sides. Upon receiving the order, all twelve Ballistas advanced in formation with the Grizzlies, utilizing their relatively small size to hide behind the grizzlies until close enough; at only eighty meters from the fortifications, the grizzlies feigned being disabled by the latest barrage, causing a lull in the fire which the ballistas took full advantage of. Storming out from behind the Grizzlies, the Ballistas opened fire with machine guns, missiles and cannons, catching the defenders off guard and forcing them into combat yet again; to further put the pressure on, the grizzlies opened back up, rending the fortifications apart with their main guns as they and the ballistas advanced. 
Tulamee had, like his troops, been caught off guard by the sudden appearance of these armored men and had scrambled to get his forces back into defensive positions; while they attempted to hold against the ever increasing enemy fire, he turned to advance his reserve force and ordered them to ignore the raiding humans and instead advance against the main human force. What he had not expected, was to see his advancing force torn to shreds as a barrage of cannon fire erupted from their flanks, causing him to again try and consolidate his forces, but it seemed hopeless, they had been surrounded and all that was left was to take as many as he could. 
At 7:32pm UTC, with the flanking Leopards ceasing fire, the Ballistas and Grizzlies together, charged through the Covenant fortifications, running down and slaughtering what troops remained hidden in the fortifications and using their explosive shells to tear apart the lines and clear any stragglers, though the main focus was the Covenant force stationed on the hill slope behind the lines. With a final charge at 7:41pm UTC, the combined UNSC force of Grizzlies, Ballistas and Leopards succeeded in breaking and then clearing the Covenant lines around Everest Base.
Subsequent recon expeditions from the base would further confirm that the Covenant had in-fact been repulsed from Everest Base. 
==Order of Battle==
===UNSC Forces===
Commanders:
*Rear Admiral Joanne Darby (UNSC Navy)
*Brigadier General Theodore Hannely (UNSC Army)
Grannus Defense Fleet: 
*1 x Orion-class assault carrier
::UNSC Highlander's Blade
*3 x Paris-class heavy frigates
::UNSC Roma
::UNSC Zulfiqar
::UNSC Roosevelt
*2 x Halcyon-class light cruisers
::UNSC Endless Summer
::UNSC Easy Goer
*3 x Halberd-class destroyers
::UNSC Gustav
::UNSC Zenith
::UNSC Jacinto
173rd Mechanized Regiment: 
*31st Cavalry Battalion
*92nd Infantry Battalion
*129th Infantry Battalion
*114th Infantry Battalion
SPECWAR/Group 7:
*88th Special Warfare Battalion
:::C Company, 2nd Platoon
*127th Special Wafare Battalion
:::B Company, Juliette Squad
:::"Windsor", 5 Ballistas
===Covenant Forces===
Commanders:
*Fleet Master Yul' Haramatanee (Covenant Navy)
*Field Master Esan' Tulamee (Covenant Occupational Force)
Fleet of Forceful Reverence: 
*3 x CCS-class battlecruisers
::Blightless Faith
::Echoing Psalm
::Rapturous Prayer
*3 x CRS-class light cruisers
::Sharpened Blessing
::Endless Devotion
::Journey's Song
*2 x SDV-class heavy corvettes
::Prophets Will
::Believers Shield
Ka'resan Legion: 
*96 Obedentiaries
*1,800 Warriors
*3,900 Thralls
*12 x Type-26 Wraith Gun Assault Carriages
*6 x Type-56 Liches
==Aftermath==
===Securing Grannus and Rebuilding===
After further recon expeditions and force deployments to all Covenant ship crash sites, as well as the wider Raymond Station, it had been confirmed that the Covenant had been defeated on Grannus, leading to celebrations amongst the few survivors; these were short-lived however, as engineering units were immediately set to work, to try and restore long range communications and allow the units on Grannus to contact the rest of the UNSC. Despite several delays and over a week of waiting, communications were restored with a long range comms station on Titan, allowing Brigadier General Hannely and other staff to report their status to the UNSC High Command; within the days it took for a response to come, the UNSC forces left on Grannus set to restoring basic amenities, in particular the subterranean farms on the edges of Raymond Station which had survived due to automated care taker systems. While this was done, a separate force made the long journey to the hydrogen mines on the other side of the habitable zone of Grannus, where several civilians were found within their bunkers, allowing the mines to start producing hydrogen and water for the survivors. 
On July 2nd, a UNSC Navy relief fleet arrived over Grannus, carrying mass amounts of supplies and equipment, much to the surprise of the forces on Grannus. Despite officially listed as lost, UNSC High Command wished to use Grannus as the jumping off point or rallying point for special operations forces conducting missions behind enemy lines, necessitating the 173rd Mechanized Regiments remnants to continue being stationed on the world, though they would be brought back up to strength. Furthermore, the 173rd would be tasked with reestablishing the output of the mines to support themselves and passing units; SPECWAR Group SEVEN and its Ballistas meanwhile were reassigned. 
===Effects of the Battle===
The Battle of Grannus was one of few victories the UNSC saw in the latter half of the Human-Covenant War; but like the others, it was at best a Pyrrhic victory as the entirety of the Grannus Defense Fleet had been destroyed and nearly all of the inhabitants of Raymond Station as well as the station itself were eliminated. Furthermore, the damage done to the facilities without people to manage them had been severe due to the solar flare and later ash storm, rendering half of the planets mines inoperable without immediate maintenance. As a result, while it had been a tactical and morale victory, Grannus was effectively a loss; The UNSC had lost a major hub of not only materials but also a major service center for traversing forces, though this was seen as a minor issue given the infrequency of advancing UNSC forces late in the war, while the Covenant had only lost a meager force of ships and ground forces. Despite the failings, Grannus became a powerful morale tool for the UNSC, as it showcased how hard and through what conditions they were willing to fight for every single colony, even a barely hospitable and sparsely populated one. While this wasn't strictly true, it served its purpose well, of galvanizing people across the Inner Colonies against the Covenant and restoring hope in those who believed their worlds were next to be destroyed. 
===Post-War Legacy===
Grannus would survive until the end of the Human-Covenant War in 2552 and became a major point of interest for the UNSC as a result of its vast material wealth; within months, numerous transports and warships had arrived on Grannus with the intent of reviving its industrial output. Similarly, this saw the rebuilding and upgrading of the Zeifer Communications Relay into a deep space monitoring station to allow the UNSC to monitor traffic within Covenant space.
===Casualties===
==Timeline==
June 9th, 2546:
[5:12am UTC] 
-ONI Listening Stations Alpha-Gamma go silent, all communication lost
[8:02am UTC]
-Zeifer Communications Relay experiences loss of connection with Deep Space Communications Satellite 
[8:15am UTC]
-2nd Platoon of 'C' Company of the 88th Special Warfare Battalion are deployed to make contact with the Seismospy Seismic Monitoring Station 
[9:57am UTC]
-UNSC Endless Summer picks up numerous slipspace ruptures outside the defensive sphere of the Fleet
[10:01am UTC]
-UNSC Roosevelt is deployed to investigate the readings, Fleet moves to standby positions. 
[10:10am UTC] 
-UNSC Roosevelt is destroyed by the corvettes Prophets Will and Believers Shield. The alarm is sounded across Grannus, the Covenant are attacking Grannus.
[10:17am UTC]
-The 129th and 114th Infantry Battalions depart Everest Base and head to Raymond Station to aid local security forces and reinforce the stations defenses.
[10:27am UTC]
The light cruisers Sharpened Blessing, Endless Devotion and Journey's Songenter formation with the corvettes Believers Shield and Prophets Will as they head for the surface.
[10:29am UTC] 
-UNSC Highlanders Blade establishes formation with the UNSC Zenith, UNSC Jacinto, UNSC Easy Goer and UNSC Endless Summer.
[10:32am UTC]
-The sight of the UNSC fleet causes Fleet Master Yul' Harmatanee to send the Sharpened Blessing and Endless Devotion towards the surface, while the Prophets Will, Journey's Song and Believers Shield would distract the human fleet.
-The splitting of the Covenant fleet causes Rear Admiral Joanne Darby to send an interception force of the destroyer UNSC Gustav and frigates UNSC Roma and Zulfiqar, under the command of Captain Wilson Invar, captain of the Gustav.
[10:46am UTC]
-The Fleet of Forceful Reverence is engaged by the Grannus Defence Fleet.
-Fleet Master Haramatanee mobilizes his remaining battlecruisers and prepares to engage a slipspace jump behind the human fleet.
[11:03am UTC]
-2nd Platoon has made visual contact with Seismospy Station.
-UNSC Roma advises Everest Base and all nearby UNSC units that it and the UNSC Zulfiqar are engaging two Covenant light cruisers headed to the surface.
-Anti-ship weapons in Everest Base are activated and recon elements are deployed around Raymond Station
[11:27am UTC]
-Fleet Master Harmatanee advises his other battlecruisers to link up with the Prophets Will and Believers Shield after the destruction of the Journey's Song. He then initiates his plan to pin point jump behind the human fleet.
-Sensors on the UNSC Endless Summer register another slipspace rupture outside their cluster, causing the recalling of the UNSC Gustav from interception to help the fleet. 
[11:52am UTC]
-UNSC Roma manages to knock out one of the engines of the Sharpened Blessing causing a mass exodus of externally mounted Liches.
-2nd Platoon is securing Seismospy Station, the civilian personnel are gathered together in transports and are escorted by Warthog, back to Raymond Station. Lieutenant Montoya receives word that the cruisers being pursued have broken atmosphere and were deploying mass amounts of troops in the direction of Seismospy Station, causing 2nd Platoon to set up defences. 
[11:57am UTC]
-Rear Admiral Darby reconciles her ships into defensive positions above Raymond Station after the appearance of the battlecruisers Echoing Psalm and Rapturous Prayer. 
-Several Longsword squadrons are deployed for combat air patrol by the UNSC Highlanders Blade, Endless Summer and Easy Goer
[12:00am UTC]
-Sensors on the UNSC Highlanders Blade and Gustav pick up a slipspace rupture behind the fleet.
-The Blightless Faith exits slipspace behind the Grannus Defense Fleet and routs all power to its weapons 
[12:03pm UTC]
-UNSC Gustav plots an attack vector to ambush the Blightless Faith from below
-The UNSC Jacinto suffers heavy damage from a plasma cannon broadside fire by the Blightless Faith. UNSC Easy Goer suffers damage to both its engines, leaving it immobile, causing the UNSC Highlanders Blade to come around and engage the Blightless Faith, along with the Endless Summer and Zenith.
[12:04PM UTC]
-UNSC Zenith and UNSC Endless Summer engage the Blightless Faith, which takes evasive maneuvers 
-UNSC Endless Summer manages to strike the aft hangars of the Blightless Faith before its shields can be raised. 
[12:06pm UTC]
-The Blightless Faith returns fire, targeting the striking the charging MAC of the Zenith, causing critical damage, and strikes the forward hull of the Endless Summer
[12:08pm UTC]
-A barrage of plasma torpedoes strikes the hull of the UNSC Highlanders Blade, compromising several compartments and hangars.
-The Endless Summer engages the Blightless Faith with MACs and Archers, along with supporting fire from fighter squadrons, the UNSC Zenith and Highlanders Blade, breaching its shields at the cost of their ammo and several fighters.
[12:12pm UTC]
-Lieutenant Montoya contacts the UNSC Zulfiqar for fire support as numerous Liches near the station.
[12:16pm UTC]
-Fleet Master Harmatanee orders the battlecruisers Echoing Psalm and Rapturous Prayer to advanced on the Grannus Defence Fleet to relieve pressure on his ship.
-The Blightless Faith returns fire, striking the Endless Summer with its plasma lance and further damaging the Zenithand Hghlanders Blade with plasma cannons
[12:21pm UTC]
-UNSC Zulfiqar and UNSC Roma launch several missiles and fire cannons as they pass Seismospy Station, destroying several Liches and damaging the others before refocusing on the two light cruisers.
-2nd Platoon enters a protracted firefight at Seismospy Station
[12:23pm UTC]
-UNSC Gustav launches a surprise attack on the Blightless Faith disabling both its engines and striking multiple points on the hull, causing it to fall towards Grannus.
-The Blightless Faith returns fire to little effect and slowly falls to the surface. 
[12:32pm UTC]
-The UNSC Roma forces the Endless Devotion away from Raymond Station while the Zulfiqar continues to chase the Sharpened Blessing
-Shipmasters of the Echoing Psalm and Rapturous Prayer enter heated talks of which shall lead the fleet and what they shall do.
[1:01pm UTC]
-After effecting temporary repairs and evacuating the crippled ships, Rear Admiral Darby reorganizes her ships in a defensive perimeter above Raymond Station.
[1:09pm UTC] 
-UNSC Zulfiqar manages to land several more hits on the Sharpened Blessing, including one with its MAC, gutting the reactor and causing the light cruiser to crash on the edge of Raymond Station. UNSC Zulfiqar remains on hand to provide support in clearing the crash site 
[1:13pm UTC]
-UNSC Roma destroys the Endless Devotion with a combined missile and MAC strike. Roma rejoins the Zulfiqar in aiding the forces in Raymond Station.
[3:02pm UTC]
-UNSC Roma and Zulfiqar detect the falling Blightless Faith on sensors and move to engage. Both are critically damaged and crash outside Raymond Station and letting the Blightless Faith deploy its forces and then crash in Raymond Station, killing thousands.
[3:04pm UTC]
-UNSC Roma manages to warn Everest Base of the Blightless Faith before it crashes. 
[3:10pm UTC]
-Lieutenant Montoya has Seismospy Station brought back online which warns of an abnormally large and powerful solar flare. The information is passed on to Rear Admiral Darby.
-2nd Platoon is assaulted by Covenant forces as the station is activated.
-The Bligthless Faith crashes into the heart of Raymond Station, wiping out thousands with its weapons and mass, the 114th and 129th Infantry Battalions are eliminated. 
[3:22pm UTC]
-The star Grannus orbits releases an abnormally large solar flare, knocking out long range communications systems across Grannus and damaging systems in both orbiting fleets. 
-Rear Admiral Darby utilizes the solar flares weakening of the Covenant shields and sensors to launch a suicidal attack against the fleet
-Recon elements of the 173rd report numerous Covenant forces emerging from the crashed Blightless Faith which begin slaughtering any and all survivors in the station. 
[3:31pm UTC]
-Everest Base deploys recon teams to investigate Raymond Station.
[3:58pm UTC]
-Rear Admiral Darby announces her intent to enact the Cole Protocol on all UNSC channels.
-2nd Platoon manages to defeat the attacking Covenant force. 
[4:00pm UTC]
-Rear Admiral Darby enacts the Cole Protocol and assaults the Covenant fleet at close range with multiple Shiva-class nuclear weapons, destroying them and her own fleet.
[4:03pm UTC]
-With no long range communications, Lieutenant Montoya orders her men to set about demolishing Seismospy Station. 
[4:11pm UTC]
-Everest Base deploys armored recon elements of the 31st Cavalry Battalion to set up short range comms beacons but is stopped by an advancing Covenant Legion under Field Master Esan' Tulamee. The Siege of Everest Base begins.
[4:39pm UTC]
-Field Master Tulamee nears Everest Base and his forces are fire upon by the base defences, incurring heavy casualties.
[4:41pm UTC]
-The Field Master responds with counter fire from Wraiths, destroying several turrets and breaching sections of the base near the surface, causing them to be sealed off. 
[5:30pm UTC]
-The core of Seismospy Station is packed full of fusion coils and demolition charges, 2nd Platoon has evacuated to a safe distance and detonates the charges, destroying the Station. 
-Brigadier General Hannely orders the construction of an underground tunnel to the east, to allow him to deploy his units. 
[6:02pm UTC]
-2nd Platoon comes across the crash site of the UNSC Roma and recovers survivors, equipment and vehicles before taking shelter inside the ship. 
[6:22pm UTC]
-Field Master Tulamee reinforces his positions with pieces of the crashed ships and begins assembling his forces. 
June 11th, 2546
-2nd Platoon begins raiding Covenant positions in an effort to delay the inevitable assault on Everest Base
June 14th, 2546
-A series of short tunnels with holes leading to the surface are built to allow counter artillery fire.
20th June, 2546
[1:27pm UTC]
-Sensors in Everest Base manage to pick up an impending raid from 2nd Platoon, causing Brigadier General Hannely to order counter battery fire.
[1:32pm UTC]
-Six Grizzlies and ten Leopards are deployed to assault the Covenant positions, four of the Leopards head east to later link up with 2nd Platoon. 
[1:34pm UTC]
-Combined fire from the advancing UNSC armor deals significant damage to the Covenant lines.
-Field Master Tulamee pulls his forces back to his rear lines and waits to set off the traps in the forward lines.
[1:37pm UTC]
-All six Grizzlies push through the forward Covenant lines but are disabled by plasma mines. 
[3:21pm UTC]
-Two Grizzlies have been destroyed and the other four have run out of ammo, causing them to be scuttled by their crews. 
-The breakout attempt is deemed a failure and both sides return to defensive positions.
June 22nd, 2546
-The Raduga-super volcano begins spewing masses of molten ash into the sky above Grannus, causing massive ash storms.
June 26th, 2546
-The Eastern Tunnel out of Everest Base is completed
June 29th, 2546
[6:34pm UTC]
-Sensors on Everest Base detect massing Covenant forces which causes an artillery barrage to be fired. 
-Twenty six Leopards are assembled in the Eastern Tunnel to flank the main advance which is spearheaded by eight Grizzlies and two squads of Ballistas
[7:00pm UTC] 
-All twenty six Leopards advance out of the Eastern Tunnel at high speed and move to the flanks of the Covenant lines.
[7:02pm UTC]
-The 2nd Platoon raiders are picked up by Everest Base sensors, therby commencing Operation GALILEO.
[7:12pm UTC]
-Eight Grizzlies begin their advanced towards the Covenant lines, firing in conjuncture with Ballista squads under Windsor and Corvus to destroy the previously trapped Covenant lines. 
[7:15PM UTC]
-2nd Platoon raiders along with flanking Leopards open fire on the reserve Covenant forces, pulling their attention away from the advancing armor. 
[7:23pm UTC]
-Spotting an explosion in the Covenant lines, Brigadier General Hannely authorizes the final advance. 
-The Grizzlies, with the Ballistas in formation behind them, crash through the old Covenant lines and open fire on the remaining Covenant lines. 
[7:26pm UTC]
-The Grizzlies cease movement near the lines and pretend to be disabled, causing the Covenant to briefly cease fire and allowing the Ballistas the advantage to break through before continuing themselves. 
-Field Master Tulamee attempts to advance his reserve but they are fired upon by the flanking Leopards, sustaining heavy casualties
[7:32pm UTC]
-The Ballistas and Grizzlies initiate the final breakthrough of the Covenant fortifications, attacking Tulamee's reserve force
[7:41pm UTC]
The combined force of Leopards, Grizzlies and Ballistas finally wipe out the Covenant forces around Everest Base, breaking the Siege. 
July 1st, 2546
-Recon teams sent to Raymond Station and other major locations confirm that the Covenant have been repelled from Grannus.