Circinus Federation-Marian Hegemony War

Circinus Federation/Marian Hegemony War
Start Date 3066
Location Circinus Federation
Result Aggressor victory
Circinus Federation Marian Hegemony
Commanders and leaders
President H. R. "Little Bob" McIntyre Caesar Julius O'Reilly
Forces involved
Black Warriors
McIntyre House Guards
Numerous small mercenary groups
I Legio
II Legio
III Legio
IV Legio
V Legio
VI Legio
Cohors Morituri


The Circinus Federation - Marian Hegemony War was a brief conflict between the two Periphery nations initiated by Caesar Julius O'Reilly of the Marian Hegemony in the latter half of the thirty-first century.[1]


Marian Hegemony border, 3063

Julius O'Reilly came to power in 3063 through using his popularity within the Marian Hegemony and particularly the Marian Hegemony Armed Forces - popularity enhanced by his successful conquest of the Illyrian Palatinate that same year - and discontent over the rule of his father, Caesar Sean O'Reilly to forcibly depose his father.[1]

As Caesar, Julius was in many ways a reformer, and he pushed through many changes to the structure of the Marian Hegemony, giving citizens far greater say in how they were ruled than at any previous point and establishing the Marian Senate, while also working to secure the Hegemony's hold over the conquered worlds of the former Illyrian Palatinate and Lothian League. Despite the reforms initiated by Julius and his focus on building both unity and goodwill within the Hegemony, Julius hadn't given up his ambitions to expand the Hegemony by conquest as well. As Caesar, Julius intended to invade and annex the nearby Circinus Federation, and began laying groundwork to support an invasion in 3063.[1]

Circinus Federation border, 3063

Although the periphery world of Valerius had remained unsettled and largely undistinguished prior to 3063 thanks to little in the way of identified valuable resources, a number of highly-publicized reports from various survey missions to the world began circulating that year. The reports prompted the Marian Senate to press for the rapid colonization, something that Julius was happy to endorse; describing Valerius as a "bright jewel", Julius ensured that dozens of ships carried colonists from across the Hegemony to colonize the world.[1]

As the civilian colonization of Valerius continued the Marian Hegemony Armed Forces constructed a secret supply and logistics depot on Valerius, activity that apparently went unnoticed by the Federation.[1]

Diplomats sent by the President of the Circinus Federation, H. R. "Little Bob" McIntyre, to meet with the new Caesar in 3063 were returned in body bags, and McIntyre knew that an invasion of the Federation at some point was inevitable. McIntyre responded to the perceived threat by trying to seek out help from the Magistracy of Canopus, the Free Worlds League member state known as the Rim Commonality and the Word of Blake. The Federation was unpopular with the Magistracy and the Collection as a result of their history of being raided by Circanian pirates, but both nations were warier of continued expansion on the part of the Hegemony and even though neither could openly aid a bandit kingdom, each hired a number of small mercenary concerns to augment the Federation forces.[2]

The Federation used the mercenaries provided by their allies of convenience to instigate rebellions on both Illyria and Lothario, actions that kept two Marian Legions, IV Legio and V Legio[3] - the former incorrectly identified as II Legio in some places[2] - occupied and pinned in place, unable to participate in Julius' invasion.[2] From the Marian perspective, the activity on both worlds appeared to be a combination of low-level insurrections and pirate activity; Julius had to change his invasion plans to adjust to IV Legio and V Legio being unable to participate, but was still determined to press ahead with the invasion.[1]


Wave One[edit]

The invasion began in January 3066 with planetary assaults being launched by the MHAF against the worlds of Blantleff and Maximillian.[1] The first Legion to attack was III Legio, who were given the honor of leading the first wave and were responsible for seizing Maximillian. III Legio swiftly broke the defending forces as VI Legio landed on Blantleff.[3] Both Legions swiftly conquered their targets in a matter of weeks, in part aided by the welcome they received from the local populations, who viewed the Marians as liberators as much as they did conquerors. The first wave of the invasion was brilliantly executed and a complete success, encouraging Julius to press ahead with the second wave.[1]

While the Marian forces seized Blantleff and Maximillian, McIntyre used some of the mercenary forces made available to him to attack III Legio and VI Legio; while the mercenaries were little better than cannon fodder they succeeded in making repeated hit-and-run attacks that helped to tie up both Legions.[3]

Wave Two[edit]

Julius targeted the Federation capital world, Circinus, with the second wave of his invasion.[1] Landing on Circinus with the combined might of I Legio and II Legio[3] (the latter erroneously being referred to as IV Legio in some places)[2] but was faced with far heavier resistance than he had expected.[1] The attack in February 3066 prompted McIntyre to make various concessions to the Word of Blake in exchange for military assistance; the Blakists responded by reinforcing both the McIntyre House Guards and the Black Warriors with new, redesigned BattleMechs. McIntyre had elements of both units disguise themselves as elements of IV Legio and used them to rob the invasion of momentum.[2]

With the mercenaries on Blantleff and Maximillian already tying up Marian forces, McIntyre had the disguised House Guards and Black Warriors land in the rear areas of III Legio on Maximillian in February, imitating reinforcements from IV Legio before attacking the Legion.[2] The attacks inflicted heavy damage on III Legio,[3] and a month later the Circinian forces attempted the same deception against VI Legio on Blantleff.[3] They met with less success against VI Legio, as the Legion had been made aware of the deception and launched a ferocious counterattack in defiance of the new heavy weapons deployed by the Federation forces; the attack kept VI Legio in place on Blantleff, but VI Legio was ultimately successful and made extensive use of captured salvage while rebuilding.[3]


With the invasion stalled, the McIntyre House Guards returned to Circinus to reinforce the capital while the Black Warriors went into hiding. Despite the attacks on Blantleff and Maximilian Julius and both I Legio and II Legio made steady progress through the heavy defenses around the Federation's capital city, prompting McIntyre to use his last trump card.[2]

McIntyre ordered the Black Warriors to come out of hiding expressly to launch an attack directly against Alphard, the capital of the Marian Hegemony. A battalion of the Black Warriors[3] battled with the planetary defenders, the Cohors Morituri, and secured the planetary HPG, sending word of their presence on the Marian capital world to Julius and his forces.[2] The Cohors Morituri tore into the Black Warriors in three ferocious engagements that broke the Circinian unit and leaving only a few Circinian MechWarriors alive;[3] nonetheless, the Black Warriors had achieved McIntyre's goal.[2]

Within days of receiving the messages from Alphard Julius had halted the invasion and both Legions had left Circinus.[2] An important factor in the decision to withdraw made by Julius was the knowledge that his Legions had faced at least eight reinforced BattleMech battalions-worth of Circanian forces, twice the numerical strength the Federation had been known to possess prior to his invasion; the Marian forces had given a strong performance, but Julius was unwilling to see what further support McIntyre had managed to gain.[1]


Marian Hegemony border, post invasion

With Marian forces securing the Hegemony's hold over Blantleff and Maximilian, Julius brought I Legio back to Alphard at speed. Although the Federation and the Hegemony were still technically at war in 3067 - the envoys Julius sent to Circinus returning without their heads at the orders of President McIntyre - actual combat had ended the year before, and Julius assigned Valerius and the two conquered Circanian worlds to the Illyrian district of the Hegemony for administrative purposes.[1]

The war was considered to be a victory overall by the Marian Hegemony, although not the success that had originally been anticipated. Prevented from completely annexing the Federation, the Hegemony nonetheless gained three worlds, a considerable amount of combat experience and a not insubstantial amount of salvage.[1] Both I and II Legio brought back substantial quantities of salvage from Circinus itself; along with rumors that the Marian forces had sacked the capital and McIntyre's military headquarters, II Legio also captured enough new 'Mechs and advanced weapons to fill a Mule-class DropShip, all of which had been intended to supply the Black Warriors.[3]

Information obtained from those prisoners taken by the Cohors Morituri revealed the complicity of the Word of Blake in the Federation's sudden increase in military strength, although none of the captured MechWarriors survived their injuries. Julius ordered that each Legion should be rebuilt to a full five cohorts of 'Mechs[3] and the Hegemony adopted a defensive posture in the aftermath of the invasion, with Caesar watching to see what the Federation's next step would be.[1]

The Circinus Federation lost two worlds to the Hegemony but survived the invasion; the long-term consequences of the campaign were unknown at the time, but the Federation was left firmly in the Blakist camp, with some regarding the Word as the Federation's new masters. President McIntyre died of a sudden heart attack in 3067 and the Black Warriors disappeared after McIntyre's death, causing intense speculation; the Blakists established a BattleMech factory on Baltazar III, the first such factory anywhere in the Federation, but the continuing expansion in military growth didn't prevent suggestions that the Federation government was now nothing more than puppets of the Word of Blake.[2]


  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 Field Manual: Updates, p. 194-195, "Historical Brief"
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 Field Manual: Updates, p. 197, "The Caesar's War"
  3. 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 Field Manual: Updates, p. 195, "The Marian Legions"



  • Start Date - January 3066
  • End Date - 3066