Illium at War concerns Illium's involvement in the Reaper War. Although not a major theatre in the war, the Tasale system fell under assault by the Reapers during the general advance after the fall of Earth, and remained under threat from hostile forces until the war's end.
With canon information on Illium's fortunes during the Reaper War being limited to a few cursory facts, a great deal more non-canon extrapolation and outright invention has taken place than would normally be the case for a canon location. The following is, therefore, naturally subject to alteration to accomodate any future information included in DLC or other canon sources.
Assault on the Tasale system
A direct threat to Illium was foreshadowed by the loss of contact with Talik and Vantage, neighbouring systems projected to be avenues of approach for an invasion of Tasale. Illium's ruling Board of Governors made no formal statement concerning the Reapers - the nature and extent of their forces still being uncertain at this early stage of the war - but enacted a range of emergency measures, including placing the Nos Astra Exchange under a temporary freeze to halt panic selling, and entering talks with several private corporations in possession of military assets.
Several days later, Reapers transited the Tasale relay and advanced on Illium. The Board judged the Reaper vessels' threat too great to permit safe departure from the system, and ordered all civilian vessels grounded. Elements of Illium's Tasale Fleet engaged the oncoming Reapers - identified as Destroyer types and lighter units only - while the major cities projected as Reaper landing sites commenced evacuation.
Tasale Fleet's strength was insufficient to halt the advance, and some Reaper vessels breached the defensive line and began surface attacks. However, despite significant damage, and loss of life at some evacuation points, much of the population under threat were able to be moved to secure locations. Meanwhile, Tasale Fleet enacted the Board's contingency plan, abandoning attacks against Reaper warships in favour of precision WMD strikes against troop carriers. Although Fleet losses were high, the strategy succeeded in denying the Reapers the immediately available ground forces necessary to rapidly expand from their bridgeheads.
The Siege of Illium
With a number of major cities, including Nos Astra, now in Reaper possession, but the ground advance blunted, those areas to which populations had been evacuated were able to shore up their defences. Many smaller settlements fell under attack from orbit, and were quickly abandoned amid catastrophic losses, but the largest secure cities managed to mount sufficient anti-air and anti-orbit defences. Reaper ground forces consolidated their positions and began rebuilding the forces diminished by their troopship losses, scouring all contested areas of the planet for victims to convert to husks, and launching periodic raids against the remaining cities.
Nos Varda - a satellite city to Nos Astra, and the destination of its evacuees - became the de facto planetary capital during the siege, protected by heavy defensive installations, barrier projectors, and a combined force of Illium huntress cadres and forces of the Eclipse mercenary consortium, which accepted effective nationalisation for the duration of the war in exchange for lucrative concessions. Although Reaper forces based in nearby Nos Astra mounted constant small-scale probing attacks, and several large assaults (including one later dubbed the 'Battle of Nos Varda', which succeeded in breaching the city's barrier lines, threatened key military installations, and inflicted significant civilian casualties before being repulsed), comprehensive scouting and sabotage operations conducted by huntress/Eclipse forces prevented the Reapers from amassing sufficient husk forces to overwhelm the city.
In addition to seeing to its own survival, the Nos Varda Provisional Authority, formed from the survivors of the Board, took a supervisory role among the remaining cities, coordinating system defence and prioritising incoming resources. Surviving units of Tasale Fleet concentrated on harassing Reaper vessels wherever possible without incurring prohibitive losses, emplacing stealthed FTL communications buoys to periodically replace those detected and destroyed by Reapers, and providing escorts and diversionary attacks to allow supply convoys to enter the system and reach Illium's cities.
Despite the deadly nature of the Reaper assault on Illium, strategists analysing their behaviour concluded largely unanimously that their primary goal was simply to halt commercial activity in the system, thereby destabilising the Terminus Systems economy in general. So long as this goal was achieved - which it was for the duration of the war - the capture and/or destruction of Illium's population appeared to be a secondary priority, pursued only as and when the forces already present in the system could muster sufficient offensive momentum without requiring reinforcements from Reapers already committed elsewhere.
The first indications of a Reaper offensive against Illium.
Where were you when the Reapers hit Nos Astra?
CDN member Daia T'Nara reposts announcements from Illium's authorities, as well as a number of other sources, chronicling the war from a civilian perspective.
Even during the war, business manages to continue - and, typically of Illium, court controversy.
The Reapers mount their largest assault on Nos Varda, forcing a desperate defensive action to halt them (and, in the process, rid the galaxy of another unspeakable menace entirely).
With no end to the Reaper onslaught in sight, news of Cerberus's attack on the Citadel pushes some to breaking point.
Ana'Therion returns to her bondmate and discovers the new reality of Illium.
Eclipse, in the person of Major Nassa D'Veyra, plans a mission to occupied Nos Astra.
Following news of the fall of Thessia, Linya M'Tanis and Daia try to keep one another's spirits up.
The Eclipse mission to Nos Astra gets underway.
Nassa live-streams video footage from the culmination of her Nos Astra mission.
Daia welcomes Nassa to the Apricity club for some well-deserved R&R following the Nos Astra mission.