Good ArticleZOD icon
Annual Award Heroic This article, Sirona (Groombridge 1618 b), was voted as the Heroic Article of 2016 in the 2016 Annual Halo Fanon Wikia Awards.

Annual Award Best Location This article, Sirona (Groombridge 1618 b), written by Timothy Emeigh, was voted as the Best Location of 2016 in the Ninth Annual Halo Fanon Wikia Awards.

40px-Terminal.png This article, Sirona (Groombridge 1618 b), was written by Timothy Emeigh. Please do not edit this fiction without the writer's permission.
Help This article, Sirona (Groombridge 1618 b), is currently under active construction.
Sirona - Groombridge 1618FlagPhase1
  • Groombridge 1618 b
General Information

Ursa Major


Groombridge System


Groombridge 1618

Orbital Characteristics

71,515,079.647 km


75,090,833.630 km

Semi-Major Axis

73,302,956.639 km

Semi-Minor Axis

73,281,150.017 km

Hill Sphere

669,676.233 km

Mean Radius of Orbit

5,217.892 km



Orbital Period
  • 153.461 Earth Days
  • 132.047 Sironan Days
Mean Anomaly

306.789° (at epoch)


7.924° (from stellar equator)

Longitude of Ascending Node



Sirona I

Physical Characteristics
Mean Radius

5,217.892 km

Equatorial Radius

5,227.507 km

Polar Radius

5,208.277 km

Aspect Ratio





5.962*10^11 kg^3


3.048*10^24 kg

Mean Density

5.112 g/cm^3

Equatorial Surface Gravity

7.471 m/s^2

Sidereal Rotation Period

27.892 Earth Hours

Axial Tilt


Average Temperature

17.2 °C

Maximum Temperature

59.72 °C

Minimum Temperature

-88.712 °C




128,244,458 (2544)

  • Nitrogen: 79.183%
  • Oxygen: 20.443%
  • Argon: 0.223%
  • Carbon Dioxide: 0.093%
  • Neon: 0.044%
  • Other Elements: 0.014%

Sirona, officially known as Groombridge 1618 b, is a small UNSC colony in the Groombridge System, the first and only planet in the system, with the object formally suspected to be a gas giant in orbit around Groombridge 1618 in the early 21st century proven to be nonexistent. It is notable for the large number of resources that have uses within the medicinal industry, leading to the planet's development as a industrial world focused on the production of drugs and other medical supplies, leading to it being a target during the Insurrection and proving quite useful during the Human-Covenant war. Additionally, while not visible from the surface, a large number of Forerunner structures sat buried in the crust of the planet.

Sirona was one of the few UNSC controlled planets to escape the war still under UNSC control, with the Covenant refraining from glassing the surface. While the reasons they didn't do so are largely unclear, the large resistance put up by the UNSC Air Force and Navy forces in the system played a part, as well as the Covenant realizing that they only needed to blockade the planet to restrict UNSC access to the medical supplies and facilities offered by Sirona and gain control of the Forerunner ruins, an action that required far fewer ships than glassing. With the other battles that were raged in the four years of the Siege of Sirona, many UNSC historians believe that the Covenant had believed this to be the best course of action and had deployed fleets that could have enabled the glassing of the planet to other engagements.

Due to being a target in the Insurrection, the Human-Covenant war, and several post war conflicts, Sirona is one of the most war scarred planets that has never left the control of the UNSC. The largest contributor to the war damages on the planet was the 4 year long Siege of Sirona, which started in 2544 and ended only due to the diversion of the Covenant forces still in orbit of the planet to the Battle of Meridian in 2548.


In Celtic mythology, Sirona was the goddess of healing, primarily worshiped in East Central Gaul and along the Danubian limes. Particularly, she was worshiped by the Treveri. Sirona's attributes were snakes and eggs. Groombridge 1618 b received the name Sirona due to the large number of Celtic descendants, specifically Gaelic, within the original colonists as well as the large number of medicinal products produced by the planet.


The flag of Sirona.

Sirona's flag, depicted above, is another reference to the Celtic origins of the settlers, indicated by the Celtic triquetra in the center of the flag. However, it also, less obviously, alludes to the other aspects of Sirona's settlement. First, each corner of the knot represents one of the three groups that participated in the colonization of the world, the UEG, the settlers of Celtic ancestry, and the crew of the colony ship. Additionally, the olive branch wreath is a close representation of the olive branch wreath present in the UEG symbol. The circle in the knot also continues this representation, indicating the central globe of the UEG logo, though it also symbolizes the inter-connectivity between the three groups of the settlers.

The colors of the flag are drawn from Celtic traditions as well, and relate to the planet and settlers as a whole. First, the green at the top of the flag represents healing and growth when viewed in regards to the planet and colony, as it was a medicinal and agricultural world. Additionally, in terms of the people themselves, it represented the prosperity that the colonists sought.

Next, the yellow-gold at the bottom of the flag, resting between orange and yellow in hue, represents the clean air of the planet, and the confidence of the settlers in their endeavor. Another symbolic meaning of this color was the power of thought, tying into the mental effort put into the colony.

The white between the two represents the potential between between the other two colors, symbolizing a blend between healing and the power of thought. This bridge presents hope for the colonists to establish a new world for advancing research into the healing arts. Standing on its own, the white represents protection and purification, echoing the desires of the colonists on a strange world.

The final color, black, surrounding the trinity knot, represents the absorption and banishment of negativity, serving as a visual embodiment of the need for the three separate groups of settlers to work together positively in order for them to survive. Furthermore, the black served as a representation of outer space, symbolizing the challenge the settlers had overcome to arrive at their new home and the void that surrounded them. Overall, it served to remind them that, while they were cut off from others by space, this negativity must be banished if they were to survive, and, as such, they had each other to rely upon.


The Forerunners

The Forerunners maintained a strong presence on Sirona during the height of their ecumene, notably as a medical world, where the Lifeworkers researched advances in medicine and, eventually, where flood specimens were studied during the Forerunner-Flood war. As such, many of the structures were built underground to contain potential outbreaks more easily. As such, many ruins of Forerunner civilization are present under the surface of the planet, though these were not discovered until many years into the Human-Covent war in 2540.

With the activation of the Halo array in 97,445 BCE, the Forerunner presence on the planet and all Flood specimens were destroyed. Following the event, no sentient life was reseeded on the planet, leaving only plants and non-sentient animal life to populate the world for the next 100 thousand years.

Colonization and Early Years

Following its discovery in 2147, and the Interplanetary Wars in the 2160's, Groombridge 1618 b was among the potential list of planets to colonize. However, it was not until the colonization of Reach by the Odyssey in 2362, which sparked the first wave of human extra-solar expansion, that ships were sent to the Groombridge system. These ships, containing mainly settlers from Gaelic regions of the UN, landed on Groombridge 1618 b in 2368.

As the atmosphere and landscape of Sirona was already compatible with human biology, no terraforming efforts were needed, allowing for the colony to develop even quicker than many of the other Inner Colonies, surpassing even colonies that had been established one or two years prior in industrial advancement.

Research of the plants, minerals, and other resources located on the planet led to the discovery of the many medical uses for the planet's resources, leading to a large medical industry developing on the colony. Within the first decade of Groombridge 1618 b's colonization, several hospitals, industrial centers, and medical research facilities had popped up, establishing the planet as a medicinal center of the Inner Colonies. This medical focus combined with the heritage of the colonists led to the name Sirona being adopted by the inhabitants.

Increasing development of the planet carried on peacefully through the years between the colonization of Sirona and the Insurrection, leading to a few large cities. However, most of this development was in the form of large agricultural or mining facilities, enabling the colonists to harvest the required raw resources for the medical industry on the planet, or gleaming medical research facilities, with a large majority of the population living in suburban settings, rather then the cities themselves. As such, the cities remained relatively small, with the research facilities in the center, surrounded by suburban living, which itself was surrounded by farms, mines, and industrial production buildings. Overall, this format was developed over the entirety of the planet, excluding the capital city, Grannus, which housed the government, military, and interstellar trade and travel headquarters, as well as many urban living facilities, as the island on which Grannus was located prevented the massive sprawl of suburban living the large mainland mass provided for the rest of the colony.


However, a little over a century after the foundation of the colony, resistance to UNSC control in the Outer Colonies came to a head, sparking the start of the conflict known as the Insurrection in 2494. While Sirona was an Inner Colony and, as such, didn't have any rebel cells originate on the planet itself, keeping itself safe for the first few years of the conflict, the various rebel factions, such as the United Rebel Front recognized the value of having the planet under its control. With this in mind, many rebel operatives from several different cells immigrated to the population in an attempt to divert resources away from the UNSC and to the Insurrectionists, gather information for any future attacks, and sow discontent among the populace. While the first and second of these goals were successful to some degree, the third goal generally ended in failure, with several insurrectionist agents being turned in by the civilians they tried to convince to join the rebel cause. This unwillingness of the Sironan citizens to rebel against the UEG was mainly due to the excellent treatment they had received from the UEG due to the importance of their world.

This pattern of subtle manipulation of the planet continued for many of the beginning years of the Insurrection. However, later into the Insurrection, during the second decade of the 2500's, the Rebel's began to grow more organized and powerful. Holding several warships of there own, such as the Iliad, the United Rebel Front scraped together a small fleet in an attempt to break through Sirona's defenses, which were not yet as strong as they were during the Human-Covenant War. Managing to gather three larger warships, along with about a dozen smaller craft, this fleet coordinated with the insurrectionist agents on the planet to attack the military headquarters on the surface of Sirona.

This attack on the surface created a distraction which the small fleet used to jump into the system and regroup following the scattering due to the slipspace jump. Once they regrouped on the edge of the system, the fleet moved to the planet, the three larger warships and some of the larger small vessels engaging the fleet in orbit, while the rest of the vessels made a break for the surface in order to land more troops to assist with the battle on the surface. This started the First Battle of Sirona, one of the few full out attacks by Insurrectionists on a UNSC held colony during the Insurrection.

At this point in time, the UNSC had relatively few forces around Sirona, for two separate reasons. First, the UNSC as a whole was deployed more into the Outer Colonies to put down the Insurrection at the source. Additionally, with the Groombridge system being so close to Earth, it wasn't expected for it to be attacked. Therefore, then UNSC had only stationed a few light frigates in the system to defend it from pirates or petty criminals, not expected to fight a fully armed opposing fleet. As such, the three Insurrectionist vessels were able to quickly overcome the UNSC forces in orbit, aided by the element of surprise. During this quick engagement, the Insurrectionists lost one vessel to an UNSC MAC round, and crashed to the planet with just a thrusters to slow its descent, preventing any large devastation of the planet, though it still left a large gash along the trajectory of impact and created a ship boneyard in the deserts of the Sironan mainland.

The UNSC forces on the ground, however, reacted to the Insurrectionists much better, quickly quelling the initial ground assault. However, with the primary goal of the distraction being achieved, the Insurrectionist loss during the first ground engagement wasn't as damaging as it could have been, as the two remaining Insurrectionist vessels landed even more troops in the farmland outside the Sironan capital. This started the second half of the ground battle, with the Insurrectionist forces attacking the Sironan military HQ at Grannus Military Base, just outside the capital city. This attack lasted for several hours, eventually drawing to a stalemate before an UNSC task force arrived in orbit, destroying another of the Insurrectionist vessels, and forcing the other to flee. With the system cleared, the UNSC could land more ground forces and fight off the Insurrectionist ground forces, eventually forcing a surrender of the surviving rebels.

Following the conclusion of the First Battle of Sirona, the planet faced no more battles during the Insurrection. However, it returned to contributing to the war effort through providing medical supplies and training. Additionally, the inadequacies of the planet's orbital and ground defense network were revealed, resulting in the start of construction of Orbital Defense platforms around the planet, and the stationing of a permanent Marine Corpse brigade on the planet, stationed at Bodua base on the Sironan Mainland. Additionally, several new military bases were established across the planet's surface. These developments proved quite beneficial in the upcoming Human-Covenant war, but didn't see any real use in conflict until that point in time.

Human-Covenant War

During the first years of the Human-Covenant war, Sirona didn't see any conflict, like much of the Inner colonies. However, the war did effect it by increasing the production of medical supplies for military use compared to civilian use, an increased defense budget, more military control, and larger focus on the completion of the orbital defenses, from completing construction of the platform to stationing a larger fleet and the fortification of the system's Interstellar jump points, should reinforcements need to be called. All of this helped contribute to the survival of the planet during the upcoming Siege of Sirona.

However the peace on this planet was soon to end. In early 2544, Covenant vessels managed to place a tracker on one of the last UNSC vessels fleeing Alluvion. Following the series of random jumps, this vessel, along with several others, ended up in the Groombridge 1618 system, seeking the planet's medical resources to rest and recover following the long fought battle. This lead to the Fleet of Righteous Vigilance being dispatched to the planet to capture the human medical stronghold, starting the Siege of Sirona.

Siege of Sirona

Main Article: Siege of Sirona

Initial Contact

When the Fleet of Righteous Vigilance, along with several other Covenant vessels, arrived in the system, they discovered the large Groombridge Defense Fleet, comprised of 60 vessels at the time, bolstered by 24 damaged vessels that had arrived in the system from previous battles, several orbital repair stations, and the orbital defense grid around Sirona. Additionally, the Luminary on the fleet's flagship detected a vast amount of Forerunner relics under the planet, which had just recently began to be found by the Humans living on the world. This, combined with the relatively few number of vessels but relatively large number of ground forces available to the Covenant led to the decision by the Prophet of Conviction to besiege the planet, rather than attempt to wipe out the UNSC defenses around the system and glass it directly, which contributed to the extreme length of the siege, excessive ground combat, relative lack of evacuation, and overall brutality of the fight, as the Covenant forces on the ground, specifically the multitude of Zealots deployed, led to a burning dedication to break through the human ground defenses and gain control of the Forerunner artifacts, which worked in the Covenant's favor.

Sirona Ruins Entrance
An entrance to the ruins on Sirona. Built just before the Siege of Sirona.

However, several factors also worked in favor of the humans. These included the extensive spaceborne defenses of the planet, holding the Covenant vessels to the edge of the system where they could only serve to deter reinforcements, rather than directly engage, the veteran marines and large number of naval, consisting of both spacefaring and "wet" vessels, air force, and army forces available, including several ace pilots from both the air force and navy who directly contributed to the death of a large portion of the Covenant landing forces by shooting down their dropships, and the medical facilities already set up on the planet, allowing for quick but effective treatment of battle injuries, with many of the human defenders even able to get full surgeries and cybernetic replacements during the course of the battle. Combined, the advantages the Covenant had and the advantages the Humans had worked to extend the battle, with neither side truly able to get an edge, but neither side able to gain reinforcements, with the world fenced out by the fleet surrounding the system blocking the UNSC from sending new forces, and the deployment of Covenant vessels to other, more pressing battles, cutting off reinforcements for the Fleet of Righteous Vigilance.

Siege of Sirona: Phase One

The initial fighting during the Siege was in space, as the Covenant forces surrounding the system deployed massive waves of landing craft and fighters to defend them. Approaching the planet, the advancing Covenant ships were met head on by the orbital defenses, with Naval fighters and point defense turrets on the capital ships in the system, as well as the defense platforms that were in position to engage, tearing the vessels to shreds. However, the shear number of landing craft, the straight shot towards the planet, not stopping to engage, and the skill and zealotry of the fighter pilots in regards to protecting the advancing dropships, led to a portion of the Covenant ships making it through the blockade and landing on the surface of the planet. While only about two thirds of the dropships, and only about ten percent of the fighters, survived the wall of defensive fire that was thrown their way by the UNSC defense forces, the shear number that had been deployed led to several thousand Covenant forces reaching the atmosphere.

At this point, the defense of Sirona fell onto the air force, with most of the Navy vessels focusing on preventing any secondary wave from breaking through the defenses undetected. While the air force pilots fought fiercely, the same factors came into play in this engagement as did in the space battle, with the Covenant dropships making a dive for the planets surface, rather than engaging, and the remaining fighters handling the dogfighting, keeping the UNSC air force fighters from doing any real damage. During this stage, only another one percent of the Covenant fighters were lost, and none of the dropships were lost, while the UNSC lost an entire garrison of air force vessels and the few assisting Navy fighters, leading to the Covenant breaking through this second line of defense and reaching the surface.

Following the breach in the Human defensive lines, the Covenant forces landed on Sirona, mostly in Epona on Capital Island, and the Sironan Mainland Nature Reserve on the mainland. The ground forces quickly established their garrisons in these locations, but were contained for the first part of the battle by the quick response of the Army and Marine Forces located on the planet, as well as ODST's dropped from orbit, starting the long, drawn out, and bloody conflict on the surface, with neither side gaining or losing much territory. However, the Covenant did manage to push into the Sironan Mainland Nature Reserve, slowly making their way to the Super-MAC fusion reactor compound in the center of the dense forest. Contrary to this, the UNSC quickly repulsed the Covenant forces in Epona, and the "wet" Navy forces combined with the Air Force prevented any Covenant from landing on the capital island for the rest of the siege.

Siege of Sirona ODSTs
ODSTs deploying to the surface of Sirona.

Siege of Sirona: Phase Two

The long, drawn out ground campaign continued for some time, with the Covenant ships and UNSC ships holding their positions for about a year, neither side wanting to advance on the other in fear of being wiped out, the UNSC by the superior Covenant firepower at the edge of the system, out of range of the SMAC's, and the Covenant by the SMAC's and consolidated firepower of the stationary UNSC fleet, which would have had time to prepare, in orbit. However, in May 2545, the Covenant ground forces managed to seize the Sironan Mainland Nature Reserve fully, quickly disabling the SMAC fusion reactors located in the forest. Following the removal of the SMAC's from the equation, along with several UNSC ships being disabled by boarding parties over the past year, while the Covenant fleet remained relatively intact, the Fleet of Righteous Vigilance moved in to engage the UNSC Fleet in orbit around the planet. Quickly overrunning the Sironan Defense Fleet, a few Covenant frigates descended into the atmosphere to provide support for the ground troops, while the remaining Covenant vessels remained in orbit to provide defense against any potential UNSC counterattack. It was during this devastation of the Groombridge Defense Fleet that Admiral Elizabeth Whitaker was killed, leading to the commander of the "wet" navy forces, Rear Admiral, Upper Half Ross Logan, taking control of the UNSC Navy forces on and around Sirona.

Second Ground Campaign

Burning CitySiege of Sirona
Bodua City and the Sironan Mainland Nature Reserve, respectively, each burning

Even once the Covenant fleet broke atmosphere, the UNSC defenders still proved extraordinarily resiliant and, unwilling to resort to any form of glassing, mainly due to the lack of ships to carry out low altitude glassing and the risk of damaging Forerunner artifacts if it was done from orbit, the Prophet of Conviction ordered that the fleet begin to besiege the planet once more. Burning the city of Bodua and parts of the nature reserve, along the coast, with conventional plasma weapons, the Covenant withered the remaining UNSC forces in those areas. With the UNSC forces on the mainland falling back to the Maponos City Combined Military Installation, the Covenant launched a two prong attack, both besieging Maponos City and moving to take the Forerunner ruins in the mountain range near the city. While the UNSC managed to barely hold onto the city, with the conflict dissolving into Urban warfare, the Covenant managed to push through the mountain entrance to the ruins and, by May 2546, two years into the conflict, they had pushed the fight for the Forerunner ruins completely underground, into the ruins themselves.

Siege of Sirona Forerunner Cave Battle
The underground ruins on Sirona during the Siege

For the third year of the siege, the battle was waged in two major fronts, the Defense of Maponos City, and the Defense of the Sironan Ruins, as well as the heavy UNSC fortification against Covenant advances on the Capital Island. The UNSC forces on the mainland were completely severed from contact with the rest of the planet and from each other. The forces remaining in the city surviving on left over supplies from the surrounding farms, and the various buildings around the city, specifically in the center, which was the most fortified. Contrary to this, those forces underground managed to connect to the mainland headquarters, located at the Maponos City Combined Military Installation, a few kilometers outside of the city and another stronghold of UNSC resistance. However, the supply lines between the underground ruins and the installation were often rather dangerous to traverse and patrolled by Covenant, so those underground fared about the same in terms of living conditions, compared to those fighting in the city, and, at times, had to resort to sharing weapons between marines due to lack of combat supplies and ammunition, with some UNSC marines resorting to utilizing discarded Covenant weaponry, despite the alien design.

However, these two fronts fell down to one, the one in Maponos city, with the fall of the Maponos City Combined Military Installation during April 2547. With their supplies cut off and now completely surrounded, the remaining UNSC forces in the underground ruins quickly fell to Covenant forces, facing slaughter after slaughter until the last remaining forces were wiped out by June 2547. With this done, the Covenant dedicated a large portion of their forces to exploring and acquiring Forerunner technology from the ruins, with the other half of the forces that were in the ruins being redirected to Maponos City, doubling down on the last remaining UNSC forces on the mainland. It was at this time that, in an effort to better command the forces on the mainland, Brigadier General Suzanne Gaume was shot down en route to Maponos City. As such, command of the marine forces trapped on the planet fell to Colonel Helen Vasquez, who command the defense through the entirety of the Siege's final year.

Final Year

Siege of Sirona Brute
Brute attacking UNSC forces in Maponos City

With twice as many Covenant forces swarming the city, the UNSC presence in Maponos was even more hard pressed to survive, with conditions quickly deteriorating and UNSC numbers dwindling until only about an eighth of the original detachment. However, at this point, the ground forces had managed to fortify several buildings in the center of the city and casualties slowed for the UNSC and increased for the Covenant, who still refrained from directly bombarding the area, instead relying on siege tactics. While the food, military, and medical supplies from the buildings did hold out for a while, especially with the reduced numbers, eventually they began to run out, and many of the surviving soldiers fell ill, died of starvation and exhaustion, or simply lost the morale to continue fighting and broke down.

However, just when things seemed to be at their worst for the mainland forces, the UNSC garrison on Capital Island had managed to almost completely repel the Covenant and sent a group of Pelicans to resupply the forces in Maponos, who had briefly managed to get a message out due to the skills of their pilots and the recovery of a Police Pelican during a nighttime patrol past Covenant lines. Additionally, just a few months later, in March 2548, the Covenant fleet above the planet was called away to the Battle of Meridian, recovering some of the ground forces but leaving about a third behind to continue the fight. Resurging against the remaining Covenant troops, the UNSC Marines on Sirona managed to fully clear the planet by May 2548, and Naval reinforcements soon arrived. At this time, Ross Logan was given a promotion to Vice Admiral and took official control of the newly reformed Groombridge Defense Fleet. Alongside this promotion, Colonel Vasquez was promoted to Brigadier General and also had her position as commander of the Sironan Marine Brigade made official. For the remainder of the war, the planet was left alone as, while the Covenant hadn't completely removed it from the picture, its tactical significance had drastically fallen, and many years of rebuilding were required to return it to even a shadow of its former productivity. As such, the Covenant focused on higher value targets until they were eventually defeated in 2552.

Post-War Conflicts

Following the war, Sirona recovered relatively quickly compared the the vast damages it had received during the siege. However, despite the industrial recovery the planet saw, allowing it to return to its position of prime medical supply producer of the UNSC by 2555, much of the damages to the natural world remained long afterwards. As such, it is easy to see where major battles had happened on the planet, such as in the Forerunner ruins, which were heavily damaged, or the nature preserve, in which, among the new growth, large swaths of trees and shrubs remain charred and dead.

Insurrection Reignited

The recovery of its position within the UNSC once again made Sirona a prime target for insurrectionists during the post war continuation of the insurrection. While it remained peaceful through 2555, 2556 saw the planet return once more to conflict, as many discontent members of the population finally gained support from the New Colonial Alliance, who saw the value of the restored world to their cause. This support led to the discontent civilians to move from protest groups to guerilla cells, fighting against the establishment, weakening the UNSC forces on the world. While these guerilla tactics were relatively ineffective, seeing how the UNSC forces on the world had returned to their pre-siege numbers, they did provide constant distraction and fear amongst the military and civilian populace, respectively.

For the next year and a half, these guerilla strikes and terrorist attacks continued, and the small cells located on the world grew larger and more well known. While this was mostly due to their ability to remain rooted on the planet despite their weakness compared to the Sironan Armed Forces, a few of the larger attacks during the final months of the unofficial conflict began to more heavily affect the UNSC strength. By mid 2557, the guerilla cells on the planet organized into a single group and took a small industrial town in the center of the mainland continent. Fortifying this position, the rebel forces on the world officially declared themselves part of the New Colonial Alliance and started a more conventional war with the UNSC forces, though still largely focusing on defense and small tactical strikes.

This situation soon changed, however. In late October 2557, the NCA forces on the surface of the planet led a daring, two pronged assault on the UNSC forces. Deploying all of their forces, abandoning their stronghold, the insurrectionists, now under the command of NCA officers, split into two fronts, one assaulting the Maponos City Combined Military Installation and the other assaulting a shipyard just outside of Bodua city. While both of these groups distracted the ground forces on the planet, several bombers that had been acquired by the forces on the planet flew in below the radar and carried out a bombing run on Grannus Military Base. Though these bombers were shot down after the first run, enough damage had been done to disorient the UNSC Army leadership on the planet. This distraction allowed for the ground assaults on the military base and shipyard to break through the Army forces stationed in defensive positions.

At the Maponos City Combined Military Installation, the attacking rebels managed to segment off a portion of the facility and hold it as a stronghold, providing a constant distraction and running interference to prevent the military leadership from reestablishing itself in the facility, now that the Grannus base was disabled. At the shipyard, however, the rebels pushed the assault. As they advanced deeper and deeper into the facility, breaking past the disoriented, already understaffed defensive forces, they made their way to a docked frigate. Boarding the vessel, the rebels, with the help of mechanics who they had planted as undercover agents within the shipyard, managed to clear it of UNSC crews and launch into orbit, firing a missile volley at Bodua Base, temporarily disabling the Marine forces on the planet as well.

Breaking atmosphere, the stolen frigate gunned its engines directly for several of the orbital defense platforms. Grabbing the attention of the naval forces in orbit, the frigate, still operating under UNSC tags, managed to get a MAC round and volley of missiles off before its nature was discovered by Vice Admiral Logan, who had been cut off from communication from the ground. Caught by surprise, Logan made the critical error of the engagement, deploying a vast majority of the fleet's vessels to engage the single frigate, assuming that more ships were present due to the explosion of two orbital defense platforms. However, the rebels had abandoned the frigate, deploying back to the surface of the planet in dropships and several of the SOEIV's. Landing back at their garrison with stolen UNSC weapons, vehicles, and technology, the rebels left the frigate to be destroyed by an overwhelming portion of the defense fleet. However, this proved to be more of a ruse as, with the ship disabled and no longer considered a threat, the UNSC forces failed to notice that the nuclear warheads on the frigate had been armed and the reactor was set to overload. As the Admiral recovered from the embarrassment of disabling and uncrewed frigate, the combined explosive power of the multiple detonations disabled many of the UNSC ships in orbit, disoriented the others, and took out a third orbital defense platform.

New Colonial Alliance's Arrival

This rather successful mission for the insurrectionists on the planet proved to be merely an preliminary operation to the main assault on the planet that was to come. As the battle with the frigate commenced in orbit of Sirona, four New Colonial Alliance vessels, who had been waiting on the edge of the system, advanced on the planet. Arriving just as the frigate detonated, the NCA ships, stolen frigates, opened fire on the orbital defense platforms that remained facing the oncoming assault. After they disabled these with relative ease due to the surprise nature of the assault, the frigates pushed through the remaining thirty-two UNSC vessels, using their disorientation to avoid return fire. Once past the orbital defenses, the frigates descended on the planet around the insurrectionist stronghold city, deploying even more troops and equipment, before launching again and fleeing the system.

With their numbers bolstered and the Sironan military leadership in shambles, the rebels on the planet began fortifying for a full out assault on several of the major cities, with Grannus set as the primary target. Rejoined by the rebels that had been attacking the Maponos City Combined Military Installation, the insurrectionist military on the planet reorganized itself quickly, aiming to take advantage of the treacherous situation they had placed the UNSC forces on the planet in with their ambushes, tactically critical surprise attacks, and distraction strikes. In under two days, the rebels were once again ready to launch an assault on the UNSC, who had recovered relatively little in that time.

However, alongside the arrival of the NCA supplies and troops, new leadership took over on the planet. Now under direct command of a NCA general officer, the tactics employed by the rebels on the planet changed. Rather than deploying in large groups divided into multiple, skilled assault teams against one or two targets, the new commander broke the forces on the planet down into four land divisions with a fighter and bomber wing to provide support from the sky. Sending these divisions out to assault Maponos City and Bodua as well as each city's respective military base, this new commander made the crucial error of not separating the division, instead marching and driving them as a large cluster straight at the target, believing that he could overwhelm the worn down UNSC forces with sheer numbers. Additionally, by dedicating the fighters and bombers to other targets, namely the "wet" navy bases in the oceans of Sirona, he failed to provide adequate air support to the infantry and armored troops and, in the process, lost practically the entirety of his air assets to the unmanned drones launched by the "wet" navy aircraft carriers, as the "wet" navy was one of the few portions of the armed forces to have relatively stable command lines at this point.

As each of the four divisions approached their targets, they first encountered Sironan militia defenders, who, using the guerilla tactics loved by the rebels for the first few years of their existence on Sirona, whittled down the numbers of the insurrectionists and slowed their assault. This gave the "wet" navy enough time to defend itself against the NCA air forces and then proceed to provide air support to the UNSC troops defending each target. By the time the insurrectionists made it past the militia forces, they suddenly found themselves facing off against regrouped marines and army soldiers as well as strafing runs from the unmanned drones. In almost as little time as it took the rebel forces to run their initial strike against the UNSC forces, they suddenly found themselves pinned down in all four locations and overrun. With his assault a failure and the insurrectionist armed forces decimated, either killed or captured, the NCA general who had taken charge of the assault surrendered and ended the second attempted takeover of Sirona by insurrectionist forces. Before the year was out, the last remaining rebel forces on the planet were rooted out and Sirona was once again firmly under UNSC rule.


With both Lieutenant General Arthur Carro and Major General Phillip Cadiou killed during this assault, and the remaining members of the UNSC command structure, including Vice Admiral Logan, facing severe embarrassment for their failures which had allowed the small rebel forces on the planet to make such a large assault possible, the Sironan Armed Forces had their command structure almost completely reconfigured, with Logan entering a force retirement. Though the military forces on the planet did, once again, end up recovering fairly quickly, the high ranking officers in the new organization structure had been pulled from other locations around the galaxy from a younger selection general officers. Among these were Lieutenant General Dexter Copeland, Major General Carol Warren, and Vice Admiral Jake Mason, replacements for Lieutenant General Carro, Major General Cadiou, and Vice Admiral Logan respectively. However, Brigadier General Vasquez remained in command of the marine forces on the planet.

The New Colonial Alliance also faced a smaller amount of embarrassment due to the failure of the general who had taken over upon the arrival of reinforcements, though this was quickly brushed under the radar and the immense success of the initial moments of the assault were pushed into the forefront instead. This was used as propaganda to help drive the NCA towards the more militant stance that it held by 2558. Additionally, the failure provided much needed insight into what methods worked for the NCA and which ones didn't, allowing the assault on Sirona to show the strength of guerilla style attacks rather than full out assaults, which contributed to the lack of any future conventional attacks by the NCA in the following year, with the group instead carrying out more distraction and ambush oriented combat. As such, Sirona was one of the few planets to face a conventional battle between UNSC and insurrectionist forces.

Following the conclusion of this conflict, the scale of the engagement and the causalities on both sides led to it being considered a worse version of the similar, pre-war insurrectionist strike on the planet. As such, many Sirona natives have begun referring to it as the Second Battle of Sirona (as the URF attack was known as the First Battle of Sirona), a name that has since spread off-world, seeing popular usage by individuals, civilian and military, when regarding the battle.

Created Conflict


Orbiting around a dimmer star than the sun, Sirona is much closer to the planet than Earth is, yet still feels to have approximately the same climate. In fact, it was so similar, that very little terraforming had to be done to the colony, and humans could even survive, if not thrive, on the planet before any was done. This shocking similarity doesn't just stop with the habitability of the planet, but also in its size, though less so, with a radius that is only approximately 1,000 km less than Earths, and about 2,000 km greater than Mars's. Its surface gravity is similarly much less than Earth's, yet not much so, only about 2 m/s^2 under.

The world of Sirona is very rich in both minerals and plant life that are used for medical supplies and drugs, as well as fertile soil for agriculture. Additionally, most of the land is joined in one large mass, bordered by a large ocean with a few small to medium sized islands within this sea. This land mass sees a wide variety of landscapes, from jungles along the equator, to rolling hills and grasslands, dry savannas and deserts, and lush deciduous and evergreen forests among the more moderate latitudes, and skyward reaching mountains, frigid boreal forests, and frozen tundra wastelands along the more severe latitudes. In orbit, Sirona has but one natural satellite. This cratered moon's relatively large size in comparison to the planet, about 6% of the planet's mass, five times more than the 1.2% shown by Earth's moon, providing very large tidal forces on the planet's one large ocean.


Maponos City
Maponos, the dominant medical research center of Sirona


  • Capital Island - Largest island off of mainland
    • Grannus - Capital City, Largest city on the planet
      • Grannus Military Base - UNSC Army Headquarters on Sirona, Largest garrison for Army troops
    • Epona - Large farming community outside Grannus, Dominant agricultural region
      • Epona Air Base - UNSC Air Force Headquarters on Sirona
  • Sironan Mainland - Largest landmass on the planet
    • Maponos City - Second largest city on the planet, Dominant medical region
      • Maponos City Combined Military Installation - Combined garrison of UNSC Army and Air Force assets
    • Bodua City - Large City on the Sironan Mainland
      • Bodua Base - Headquarters and garrison for the Sironan Marine Brigade, officially known as the 19th Expeditionary Brigade
      • Bodua Memorial Hospital - Hopsital in Bodua City, utilized heavily by military during Siege of Sirona
    • Esos City - Small City on Sironan Mainland
      • Esos City Marijuana Fields - Growing fields for marijuana companies headquartered in Esos City.
    • Sironan Mainland Nature Reserve - Nature reserve on the Sironan Mainland
      • Sironan Mainland Nature Reserve Compound X - Super-MAC ground based reactors
  • Sironan Ocean - The large ocean on Sirona
    • Sirona Naval Base Alpha - Headquarters and garrison for "wet" naval vessels
    • Sirona Naval Base Beta - Secondary garrison for "wet" naval vessels
    • Sironan Ocean Air Force Base - Ocean garrison for UNSC Air Force assets on Sirona


  • UNSC Medical Facility Sirona
  • Sirona Station Alpha
  • Sirona Station Beta
  • Sirona Superior IJP Scanning/Relay Station
  • Sirona Inferior IJP Scanning/Relay Station
  • Orbital Defense Platforms
  • Orbital Repair Platforms


Sirona is heavily vegetated, more so than Earth, with large portions of the land masses of the planet being covered in forests and jungles. Several species of the many trees, shrubs, and flowers of the planet offer medicinal properties. Additionally, the vegetation on the planet is quite sturdy, due to the high amounts of winds on the planet, resulting from the larger amounts of unequal heating experienced on the planet due to the land masses and ocean being more distinctly separated, with only one large occurrence of each. Alongside the natural vegetation, many human introduced species have been planet, both for industrial medicinal use and for recreational use, such as marijuana, of which many families grew in small family plots alongside the heavy industrial production of the plant in Esos, which produced processed marijuana for recreational use both on Sirona and on other worlds.

Sirona's fauna are plentiful, with most of the species living within the jungle, and relatively few living towards the more polar climates, much like on Earth. Additionally, many species of maritime animals also exist, populating the planet's large ocean. Additionally, several species of fauna from Earth are present on the world, including dogs, cats, farm animals, and several species of birds.

Many of the plant and animal species on Sirona were killed off to dangerously low numbers or even extinction due to both over-hunting, industrial habitat destruction, and the large amount of warfare that the planet saw, which heavily scarred the planet. However, over the years since the siege, extensive conservation efforts allowed for much of the wildlife to begin an upward trend and once again begin spreading over the world again. Additionaly, the plantlife was reseeded due to the extremely valuable medicinal characteristics of much of it, and has started to show signs of regrowth, though the burned husks of dead trees and brush can still be seen in various locations.

Government and Society

Sirona was one of the most important worlds for the development of medical supplies and training for medical professionals throughout the UNSC. Several of the most prestigious medical schools were located on this world, as well as buildings for several medical companies, such as Optican. Large amounts of the agriculture and mining on the world focused on growing and harvesting and extracting the required plants, chemicals, and raw materials for the creation of the medical supplies and equipment produced on the planet. As such, it relied heavily on other colonies for their food products and other necessities. Most cities on the planet's, excluding the capital city, Grannus, which had housing for the government officials that worked in the city, had relatively few residential centers, as the urban community was reserved for medical schools, corporate buildings, research centers, hospitals, and other similar structures relating to the economy of Sirona.

Most of Sirona's original settlers originated from areas with heavy Celtic influence. As such, the colony has large Celtic influence itself, even present in its common name, Sirona. As such, the most popular languages, besides English, were all Celtic languages. Even when other colonists settled on the planet, the Celtic influences remained strong, and are still noticeable on the colony.

Grannus, the capital city of Sirona

Sirona had is own government, located in Grannus. However, it was overseen by the CAA and later the UNSC and UEG following the absorption of the CAA. Sirona in its entirety never joined the insurrection like many other colony worlds did. However, following the war, several discontent groups within the populace grew into guerilla insurrectionist cells. Additionally it was subject to a few attacks from groups such as the United Rebel Front due to the medical supplies present on the planet.


Main Article: Sironan Neopaganism

While Sirona had no official religion, and many small groups of various practices were present on the world, by far the largest was a sect of Celtic Neopaganism developed about twenty years after the original colonists arrived known as Sironan Neopaganism. A revival of Celtic Paganism in modern times, the pantheon was reorganized to feature Sirona as the primary goddess, inspired by the planet's name. One of the major aspects of the religion was the belief that the world of Sirona actually embodied the idea of the goddess herself, with the various lesser gods and goddesses making up the various aspects of the world. As such, the pantheon itself is seen as one goddess, Sirona, who is composed by the various other gods and goddesses to create the whole.

Following the Siege of Sirona and the scattering or death of many of the world's original inhabitants, the primary branch of the religion changed from that of organized gatherings and the original beliefs to a more nomadic religion, with individual practice and a focus on the individual doing what he or she could to one day restore the world of Sirona and 'heal' the 'broken goddess'. This new branch became vastly more popular galaxy wide as its followers were more spread out and sharing their beliefs on other colonies rather than simply centralized on the homeworld. By 2558, 87% of those practicing Sironan Neopaganism were of the branch formed during the Siege, while 8% were followers of the orthodox branch, mostly those who had returned to the world to rebuild following the war, and the remaining 5% were followers of various other minority branches.


Though Earth was the UNSC's cultural, political, and commercial center of the UNSC, and Reach was the military center, Sirona was the medical center of the human colonies. As such, it was still afforded an extensive defensive grid. Though not as advanced or possessing as many large vessels as Reach's or Earth's, it still held a large fleet of frigates and destroyers.

The Groombridge Defense Fleet was made up of anywhere from 50 to 60 warships permanently. Additionally, there were 10 semi-mobile orbital "Super-MAC" defense platforms. Finally, 5 refit platforms were held in orbit above the planet. On the surface, a large detachment of UNSC Marines were permanently stationed to supplement the Army and Air Force forces present on the planet. It held one of the largest complements of Air Force personnel and assets out of all of Humanity's colonies.

  • Total Available Military Manpower: 70,276,132
  • Total Land Personnel: 97,214 [15,350 Marine, 61,800 Army, 20,064 Militia/Paramilitary]
  • Total Naval Personnel: 170,217 [19,515 Sailors (18,515 Ships, 1,000 ODPs), 16,344 Embarked Marines/ODSTs (15,594 Ships, 750 ODPs), 116,158 Ground Personnel, 13,200 "Wet" Navy Sailors, 5,000 "Wet" Navy Ground Personnel]
  • Total Naval Assets: 65 Space-faring Vessels, 100 "Wet" Navy Vessels [4 "Wet" Navy Carriers, 6 "Wet" Navy Aviation Cruisers], 5 Orbital Defense Platforms
  • Total Air Force Personnel: 15,100
  • Total Air Vehicle Assets: 3,672 (600 Air Force, 2,500 Civil Air Patrol, 500 "Wet" Navy, 72 Navy)
  • Serviceable Airports: 823
  • Defense Budget: cR. 27,224,000,000

(all numbers as of 2544)

Notable Sironan Natives


List of Appearances

(Disclaimer: All images used are either Bungie/343 Art used under fair use, created by the author, images under free use licenses, or used with the permission of the original author. If any of your artwork was used without meeting these restraints, please contact me, and I will remove the image from the article until a resolution can be reached. Copyright infringement is not my intent.)