Imperial Navy Deep Recon Probes deployed to the Angel-Crimson Pass North Sector had detected FTL signatures consistent with jump-drives many cycles before the start of the war. As early as 4498 A.D, the Imperial Navy's Intelligence Branch had documented what was believed to be large-scale fleet movements on the edge of the Taran Nebula. The Imperial Government was, as such, well informed about such developments for many cycles. The Directorship had predicted a large-scale conflict with the aggressive, largest member of the Cordial Trade Alliance for many years, such developments had seemed to lead credibility to those simulations.
As such, plans were put in place well before hostilities commenced, in accordance with The Directorship's long-term vision for humanity's survival. Such prudence no doubt paid off in the early stages of the war as the Imperial Military forces were more than prepared to stave off a potential invasion fleet, or at least slow it down sufficiently so that alternative measures could be put in place.
Initial intelligence reports gathered from DRPs deployed to the Crimson-North region, and indeed, the border to Tyandirric space itself; the Taran Nebula, had revealed low-mass FTL signatures had already transited the Angel-Crimson Pass undetected before the probes had been deployed sometime in the middle of the 45th century; likely remaining undetected within the Angel Reach due to the small mass of the object. This object was believed to be some form of recon probe, or more threateningly, an FTL relay beacon used to stage a long-range attack bypassing the Angel-Crimson Pass entirely.
The Imperial Special Service began covert operations to identify possible exit points for the supposed-probe somewhere within the Angel Reach shortly after the first reports were compiled, in 4498 A.D. Intelligence-gathering operations were set up in essentially all of the semi-independent systems in the Reach, focusing on those simulated to be the most likely exit vector of the signature. The Helia System - the de-facto capital of the Reach, and most populated system in the Sector - was identified as a likely candidate.
In the early cycle of 4501 A.D, a local population of nomadic tribes of unconfirmed origin, inhabiting the remote desert world of Helia-1 in the Helia System became uncharacteristically aggressive towards local ISAR Corporate mining interests operating on the surface of the planet. Initially, the response was handled by the Helian Planetary Defence Forces with support from the Helian Navy, but the cause of this aggression soon became of interest to the Imperial Special Service.
After the nomads launched a full-scale assault on HPDF positions on the planet, it became clear something had agitated the locals. The counter-attack by the HPDF forces on the planet was watched closely by the ISS but no intervention was made until information on a nomadic 'skiff' destroyed by the defenders was decoded. The databanks had information regarding a 'sign' the locals believed had been sent by their 'God' from the stars; detailed descriptions and accounts of the event included information seemingly confirming that an space-borne object had collided with the world sometime that cycle.
Immediately, the ISS elevated the priority of the operation to a Strategic Level and the Imperial Navy's Angel Sector Command activated a Special Response order to the Angel Sector Fleet's 1st Rapid Response Fleet. Time was crucial, since the probe had likely already been transmitting FTL exit data to the alien aggressors for most of the cycle; it was deemed that an invasion of the Angel Reach by the Tyandirric Third Imperium was imminent.
The ASF 1RRF was dispatched immediately from Fleet Staging zones in Angel A20 and Helia itself. A large contingent of 1RRF assets were already present in-system near Helia Prime (Helia-2); an extensively populated world newly integrated into the Imperial States. The flagship of the Angel Sector Fleet, and mobile Command Centre of ASF High Command; the RT-class Dreadnought By Their Sanction was permanently attached to the world's orbital defence force. With short notice, a Task Force was assembled from the 1RRF's newly created First Response Group equipped with the new VE-II class Heavy Cruisers and upgraded RE-III class Battlecruisers. These vessels were part of the upgrade package developed for the Imperial Navy to counter the threat of the Tyandirric fleet.
A Civilian Outpost orbiting Helia-1 dispatched an emergency distress signal at approximately 1410 LST (Helia-1), indicating the arrival of multiple unidentified high-mass objects approaching the world at high velocity via an apparent FTL exit vector very close to the planet itself, and some mere ~50 kilometres from the Station itself. A Helian Navy Farlease-class Light Cruiser, Stormer, was also present.
1RRF's First Response Group entered FTL with exit trajectories aligned for the Civilian Outpost almost immediately, with the Group Commander making the decision to punch the fleet out at knife-range in order to attempt to save Helia-1's orbital infrastructure from destruction. The First Response Group's forward element consisting of the VE-II-class Heavy Cruiser Tromen and the RE-III-class Battlecruiser Alexander Yordanov along with a pair of RV-class Fleet Cruisers and a trio of SP2-class Destroyers exited subspace approximately ~40 kilometres away from the Civilian Outpost and almost immediately made contact with identified hostile warships at ~ 1418 LST (Helia-1).
(Above) ASF 1RRF's First Response Group forward element breaks FTL and immediately engages identified Tyandirric warships approaching the station. The footage was created by a civilian tug operator near the station complex.
Due to the Group Commander's decision to punch out at CQC range, there was insufficient time to align the Group for axial weapons discharge, as such which is highly unusual in Imperial Navy doctrine, the group engaged with directed weapons almost immediately after exiting Sub Space. It is believed the Imperial Navy's timely arrival was not anticipated by the alien aggressors, who may have been unprepared for a full-scale fleet engagement at the time. 1RRF's First Response Group successfully repulsed the initial Tyandirric assault fleet which consisted of a single super-capital warship (identified as a Dreadnought), two escorts (identified as Strike Cruisers) and a new warship previously undocumented, believed to be a landing craft for planetary assault.
The initial engagement salvo from the Group consisted of a pair of SPARTAN-IV-E Anti-Ship Missiles with Electromagnetic Impulse warheads launched from Alexander Yordanov, along with a series of 'Slepota' Active Countermeasures to cover the fleet, followed by multiple Hornet-L Anti-Ship Missiles from the Tromen and escorting RV-class cruisers. The intention of the group commander was to disable enemy electronic systems by detonating EMI warheads in the path of the fleet and cripple precision targeting systems with Active Countermeasures as the rest of the First Response Group punched out of subspace.
The group suffered significant losses, however, with both RV-class cruisers out of action, one completely destroyed, two of the three SP-class destroyers sustaining major damage, one of which critically so, and the Group flagship, Tromen suffered major damage to her bow superstructure caused by direct impacts from the Tyandirric Dreadnought's main battery. Despite the penetration of the pressure hull, however, the up-armoured main belts of the new VE-II class Heavy Cruiser had believed to have successfully diminished the energy potential of the incoming blasts as to prevent major internal damage to her forward compartments. As such, the Tromen remained operation throughout the engagement, despite being immobilised due to the loss of functionality of her lateral de-accelerators. Alexander Yordanov suffered no damage and her shields remained operational throughout the engagement. Despite the losses, the action was deemed a Success as the Civilian Outpost was largely undamaged, along with the Helian Navy Farlease-class Light Cruiser, Stormer.
The initial Tyandirric assault force was completely destroyed, with confirmed losses of all present vessels and the Dreadnought being disabled entirely by weapons fire from the Tromen and Alexander Yordanov. The initial engagement was concluded approximately 1450 LST (Helia-1).
With the situation in orbit momentarily secured, the First Response Group moved to deploy surface forces to Helia-1 in order to attempt to secure the Tyandirric FTL beacon, intact, and somehow disable it before more Tyandirric warships arrived over the world. The Group Commander assigned an Away Task Force consisting of Imperial Planetary Forces troops supported by Imperial Marine mechanised units from the attached HY-class Fleet Carrier that had arrived with the bulk of the First Response Group's elements shortly after the cessation of the initial engagement. The Away Task Force was landed planet-side at approximately 1468 LST (Helia-1).
Upon arrival, the ATF was assigned to locate and secure the Tyandirric FTL Beacon at any cost, but also to retrieve it if possible - this was considered a high priority since the beacon would likely contain significant encoded data on the capabilities of Tyandirric FTL systems that could prove decisive for the Imperial Navy in the coming war. The First Response Group's ATF units made contact with the remains of the HPDF operating near a surface-base at 1490 LST (Helia-1) and began a co-ordinated offensive in nomadic-controlled territory in order to complete their objective.
However, at approximately 1510 LST, the 1RRF's FRG in orbit reported multiple additional FTL exit signatures at a greater distance of around 10,000 KM. Additional Tyandirric warships exited FTL and formed a phalanx moving towards the FRG's defensive perimeter around the Station at 1521 LST. The newly arrived group consisted primarily of smaller, faster escort-type vessels identified as Strike Cruisers and two additional, assumed, planetary landing ships. 1RRF FRG entered a stand-off defensive holding pattern and immediately began engaging the approaching hostile alien vessels. The Away Task Force now had additional pressure to complete the objective before the FRG's position was overwhelmed. Though additional elements from the FRG stationed over Helia-2 had arrived, the Group Commander requested immediate reinforcements with the highest priority, invoking the Angel Sector Fleet's Strategic Defence Capabilities.
Imperial Dreadnought, By Their Sanction, stationed over Helia-2 got underway at approximately 1540 LST (Helia-1) with a significant escort, moving outside of the outer orbit zone of the populated world in order to align her main battery for Extreme Range Discharge (ERD) in support of the FRG over Helia-1. This was achieved at 1572 LST (Helia-1), just as the Tyandirric strike cruisers managed to break the fire-zone established by the Tromen and her escort. Despite this, the aliens had suffered extensive losses at ranges in excess of a thousand clicks; confirming that the Imperial Fleet had significant weapons advantages at stand-off ranges that was previously ascertained by Naval Intelligence based on existing reports of Tyandirric warship capabilities. Within CQC (<1000KM) the aliens had sufficient firepower to overwhelm Imperial warship defenses fairly quickly; resulting in the catastrophic loss of multiple cruiser-class vessels of existing designs not upgraded for Tyandirric engagements. This underscored the importance of the Fleet Upgrade package that resulted in classes like the interim Thunderhead-class and the VE-II class.
Despite achieving a breakthrough of the 1000 KM threshold enforced by the First Response Group, the Tyandirric Cruisers were halted by accurate inter-planetary bombardment from By Their Sanction directed by the Alexander Yordanov's extensive precision targeting systems. This proved strategically crucial in allowing the FRG to hold the planet's orbit without allowing Tyandirric ships to land and attempt to secure the beacon themselves.
FRG's ATF reported they had engaged unknown surface combatants planetside at approximately 1600 LST (Helia-1) later identified as Tyandirric mechanised units, believed to have been covertly landed before the initial force arrived. Despite heavy fighting, the ATF successfully repulsed the alien ground forces attempting to strike the force's rear guard, supported by precision orbital weapons fire support from SP-2 Destroyers from the FRG in orbit. By 1650 LST (Helia-1) the Tyandirric cruiser groups began withdrawing from Helia-1's outer orbit and were believed to be re-grouping, likely awaiting the arrival of heavier warships through the FTL vector. However, by 1700 LST (Helia-1), the ATF reported they had completed their objective and Imperial Marine mechanised engineers had successfully rendered the alien beacon inoperable, flagging for planetary extraction by ~1750 LST.
Remaining alien warships that broke from the main assault force were systematically neutralised by 'probe and paint' tactics from the FRG directing SPARTAN-IV's from Alexander Yordanov to great effect. The Group Commander declared that the Helia-1 system was secured by 2000 LST (Helia-1), concluding the Battle of Helia-1 and the first human-Tyandirric conflict in history with a strategic success for the Imperial Navy.
Outcome
With the Tyandirric FTL beacon neutralised, and the initial invasion force repulsed; the Imperial Navy had successfully thwarted an attempt by the aliens to penetrate Aquarius directly, bypassing the bulk of humanity's strategic defences in the Angel Reach and Angel-Crimson Pass. This was a major strategic victory for ATIS, and is believed to have bought at least 5 cycles of additional time before any Tyandirric fleets could be expected to "Solar Hop" through the pass to continue their invasion of Aquarius. This time would be essential in allowing the Imperial Navy to establish its Strategic Deterrent operation.
The destruction of the Tyandirric Fleet in orbit over Helia-1 also gave the Imperial Navy a significant amount of intelligence regarding Tyandirric weapons capabilities, systems, warship structure and defensive capability. The wreckages of both human and alien warships were recovered and extensively analysed by elements from the ISS and IBNI, yielding significant data. This data, such as the damage patterns of incoming high-energy weapons used by the aliens on human warships would ultimately result in the Imperial Institute for Naval Research developing improved armour compositions and shield harmonics patterns designed specifically to counter Tyandirric weapons, that could be easily deployed to existing warships with minimal effort. Furthermore, analysis of friendly weapons fire on alien vessels would allow tuning and development of improved designs.
A significant concern during the battle was the relatively large amount of time required to pacify the Tyandirric Dreadnought with the main batteries of the Imperial capital ships. While the IM115 IMPAC was more than capable of penetrating the frontal armour of the dreadnought, the weapon's relatively small area of effect upon penetration (Particle Cannon lance penetrates solid surface, fracturing armour but similar in nature to a "sabot dart", the actual physical damage is limited to a small area). Despite the high accuracy, penetration capability and range; the lack of detailed targeting data on the Tyandirric vessels prevented Imperial warships from targeting critical systems effectively, limiting the effectiveness of the IMPAC weapons against the Dreadnought.
Analysis of the dreadnought's structure and composition allowed Imperial engineers to create detailed targeting data for gunnery systems that would allow precision targeting of sub-systems of similarly designed alien ships in the future, but continued to underscore the importance of medium-range, high area-of-effect weapons such as the Heavy Helium Plasma Cannons being equipped to new-generation Imperial warships. The Tromen demonstrated the effectiveness of these in CQC range extensively.
Despite the shortcomings against larger vessels at short range, the IMPAC cannons remained effective at their intended role; fracturing and penetrating armour panels and sub-systems. It as deemed that further intelligence regarding Tyandirric warship composition was essential in fine-tuning their effectiveness.
Along with the wreckages, multiple alien bodies were recovered and transferred to the ISS's Xenobiology Division for analysis, potentially in areas involving biological weapons. Such data would remain classified and not released to public scientific institutions, however.
Helia-1's orbit was subject to a mandatory civilian evacuation and a Restricted Zone cordon was established by the Imperial Navy covering the entire lower and outer orbits of the world in order to prevent alien wreckage from falling into the hands of freeloaders from the Angel Reach. This cordon would be permanently patrolled by the reinforced elements of the First Response Group for the first stages of the war, and Helia-1 remained one of the most strategically vital sources of intelligence on humanity's new enemy for years to come.