Background
Since the Imperial Flag was raised over the capital of the Independent States of the Angel Reach (ISAR) in 4404 A.D, largely by forced means under a guise of 'diplomacy', unrest had been brewing on the world of Helia - the seat of the now former ISAR and what was left of its military in the first few years of the 45th century. With the presence of the Imperial Retribution-II class Dreadnought, AINV Crimson Prestige, in orbit, there was little open action the former ISAR militants could engage in without suffering overwhelming losses, so they decided to lay low and bide their time. Engaging in an irregular counter-insurgency capability was considered the only option they had to at least attempt to resist the Imperial Flag hung heavy over their former 'free world'.
Many would-be insurgents simply surrendered, giving up to what was essentially impossible odds; some bought into the Imperial propaganda campaign regarding the wealth of 'advantages' of being an Imperial Citizen under the ATIS Flag, but deep within the city tiers of Helia's megacity of the same name, battle plans were drawn in an attempt to drive the Imperial troops off world.
Prelude
ISAR military commanders loyal to the freedom of their world knew open action was suicide; they faced not only superior numbers, but almost certainly superior training, tactics and equipment. The Imperial war machine was not something that could simply be 'stopped' by a relative handful of ex-military insurgents. Instead, significant time and planning was pushed into exploiting the ATIS Council's apparent 'good will' gestures to the people of Helia; one of the concessions the planetary government had managed to secure during the signing of the Imperial Treaty of Governance of 4404 was that the planet would remain, largely, under the authority of its existing independent government. Imperial involvement would be limited, at least initially, to a local embassy of sorts, with an AITS advisory council. Official power for planetary issues would still remain within the hands of the ISAR government, albeit with 'strong recommendations' on actions to take; the ever-looming shadow of the Imperial Fleet hanging in the skies above the world a stark reminder that opposition was not healthy.
The goodwill gesture had come down from the very top of the Imperial Government, from the ATIS Council Directorship itself. After all, winning the minds of human beings was almost certainly more effective than oppressing them to alignment with the Imperial Vision. That said, the seeds of rebellion had been growing for decades after the 'treaty' of 4404 A.D, the years that followed leading up the dawn of the 46th century had almost seen peace, prosperity even, but it would not last.
The presence of the Imperial Navy within the Helia system had almost entirely eradicated any criminal or pirate element activity; the system experienced the lowest rate of space-borne piracy in the history of ISAR. This reduction also brought about a subsequent economic boom as more and more traders, especially smaller start-ups, were able to operate freely within Helia's space-lanes without fear of criminal activity - or having to pay the hefty fees of private paramilitary escorts, who themselves found less and less 'work' in the core system. These advantages, many of which were already proposed to the people of Helia did, in some capacity, win over the hearts and minds of many Helians in the first few decades. However, increasingly draconian invasions of their supposed 'freedoms and liberties' took place each year, culminating with the mandatory introduction of the gene-editing Universal Compliance Network in 4491 A.D.
Previously, the UCN wasn't mandatory for citizens under the ISAR's independent government on Helia, like it had been for citizens within Central Aquarius; the writing had indeed appeared on the metaphorical walls for some time, but many Helians were keen to live in a dream that they would somehow be spared force inclusion in the Network.
With the start of the Aquarian Civil War in 4461, there was even some small seeds of hope that the Imperial Government would be overthrown, to be replaced by a more libertarian federation like of the days of old, yet the fledgling secession states of the Eridonia Free Peoples Fleet would soon crumble before the war even gained momentum, with the invasion of the EFPF home system, Old Bastion's Star in 4462 A.D.
With the seeds of rebellion in central Aquarius crushed, the dawning inevitability of forced implantation of genetic modifications under the UCN was now looming. During the years following the collapse of the EFPF, the Imperial Advisory on Helia engaged in a long and expansive propaganda campaign about the advantages of inclusion in the UCN, even going so far as to claim membership was 'voluntary'; hoping to gain enough traction with Helians so that dissidents refusing to comply could be 'removed' without major publicity. Still, the Directorship of the ATIS Council demanded that the Imperial Advisory on Helia work with the ISAR government rather than establish an oppressive occupation, much to the surprise of many who had opposed the Imperial arrival at the turn of the 43rd century.
This would, somewhat ironically, play into the hands of the ISAR old guard, who had been waiting in the shadows, exploiting the relatively diminished presence of agents operating under the banner of the Imperial Special Service's Population Compliance Department within the lower tiers of the Helian megacities. The reason for this unexpected boon was the fact that a large percentage of the Helian population had actually aligned with the Imperial way of life; something the ATIS Council was keen to protect, as per the Directorship's Vision - they would not be willing to deploy overwhelmingly destructive orbital weapon systems within the boundaries of the megacities without potentially killing millions of Imperial-aligned Helian civilians and essentially destroying any goodwill they had built up during the past decades. Imperial forces operating over the planet were almost certainly keen to avoid an open conflict whereby the full power of their warships could be deployed; limiting any military operations to small-scale incursions by special ground units - something the ISAR old guard military could very well deal with in direct combat, or at least, that was their plan.
The first plans for an armed uprising were put into place during the late cycle of 4491 A.D, when the Imperial Advisory planet-side began to roll out the first phase of the mandatory UCN implantation process; something that would all but destroy any chances of covert operation by Free ISAR sympathisers and their associates.