Timeline for a virus free Rebellion
I see the rebellion (without Virus) as a grinding, prolonged war between the major powers while a lot of trade is disrupted between war zones but relatively unaffected in far reaching areas of the Imperium.
1117
Fleets are called to action from the sectors Vland, Corridor, Lishan. Anteres, Fornast, Daugukashaag, Ilelish, Zarushagar, Massila, Delphi, Old Expanses and Daibei. Elite Naval couriers (Jump-6) using a secretive shortcut through the Great Rift had delivered the news to Archduke Norris at Regina news about the Assassinations in just 49 weeks - 2 weeks ahead of the "official" news. Dulinors' fleets clashed with Lucan's fleets in systems midway between Capital and Dlan. Solomani Confederation fleets in the Imperial border crossed it as soon as official word of the assassination reached them. The border was pushed forward some 20 parsecs. Corridor felt the sting of Vargr plunderers almost immediately. The Old Expanses was already under Solomani attack and the withdrawal of the Imperial fleet left the Sector's nobles no alternative but to surrender.
1118
The Rebellion, also known as the Second Civil War (to distinguish it from the First Civil War) and the Final War, was the undoing of the Imperium. Fleets from Corridor, The nobles of Vland Sector felt threatened by the advances of Vargr in neighboring Lishun and Corridor sectors. When Lucan demanded a portion of Vland's fleets to reinforce the assault on Dulinor, Vland refused and declared its independence as the "new" (recreated) Vilani Empire.
Lucan ordered the Daibei Sector fleet to transfer to Zarushagaar Sector to reinforce his battle lines against Dulinor. The sector nobles refused this order and announced that they would take an independent and neutral path. Imperium wide mercantile shipping hull percentages dropped by 25% due to casualties during the fighting between factions in rebellion.
1119
Duke Murata leaves his realm for the safety of Margaret's Stronghold.
Mongrebi Trade Conference officially ceases operations as the participants are now scattered by the Rebellion. Akagi Transport Corporation collapses from the effects of the Rebellion.
In 1119 the Rebellion settled down to a dedicated battle to the death between Lucan and Dulinor.
Other factions contributed their forces to resolving squabbles between them, picking away at Lucan or Dulinor or both, or just trying to survive the chaos that was enveloping the empire. Imperium wide mercantile shipping hull percentages dropped by 20% due to casualties during the fighting between factions in rebellion.
1120
The Rebellion reaches a tipping point where the majority of the Naval forces have now been destroyed.
Duchy Victoria declares Independent Duchy of Oasis as an independent state from the Third Imperium.
Aslan Hlearkhea invaded the Belgariad Sojourn and quickly swept aside the feeble defenses.
By 1120 the factions had destroyed the mighty Imperial Navy. At the beginning of the war there were 320 numbered fleets and an equal number of reserve fleets, by the end of the year there were fewer than 95 numbered and 130 reserve fleets, and those reduced to 60% strength or less. Imperium wide mercantile shipping hull percentages dropped by 15% due to casualties during the fighting between factions in rebellion.
1121
The Rebellion factions continued to hammer away at each other with what force they had left. However, limited resources dictated warfare to devolve into banditry, surgical strikes and terrorism.
The Federation of Arden announced the addition of two worlds Caloran (Spinward Marches 0911) and Rangent (Spinward Marches 1411) to the Federation. Imperium wide mercantile shipping hull percentages dropped by 12% due to casualties during the fighting between factions in rebellion.
1122
Khulam Subsector was declared an Intensive War Zone in 1118 and remained the scene of the bitterest Imperial-Solomani fighting until 1122.
Duke Starkar Beres, the subsector Duke of Promise Subsector stripped of his title by Lucan.
Economic conditions, already shaky from years of warfare, worsened. Governments in the frontier areas, formulating their own survival, became neutral or opposed the war. The factions, not having the resources to hold questionable areas, saw their areas of control shrink. Imperium wide mercantile shipping hull percentages dropped by 18% due to casualties during the fighting between factions in rebellion, Aslan and Vargr attacks.
1123
The Arrival Vengance, a Lightning class frontier cruiser leaves the Domain of Deneb under secret orders from Archduke Norris. Imperium wide mercantile shipping hull percentages dropped by 11% due to casualties during the fighting between factions in rebellion.
1124
The Corsairs controlling Rugbird/Aramis (Spinward Marches 3102) are driven off by the Domain of Deneb naval forces. Imperium wide mercantile shipping hull percentages dropped by 13% due to casualties during the fighting between factions in rebellion.
1125
The ecomomy of Drayrk collapses causing a massive social disruption and starvation of the population.
Due to lack of external funding, the corporate governship of Toraago is forced to sell most of its manufacturing equipment to offworlders and convert to agricultural production. Officials of the Exeter Federated Shipbuilders announced the establishment of a new program to ease the burden of commerce raiding that has plagued the war-torn Diaspora Sector. They will cooperate in creating sets of standardized, simplified plans for the conversion of commercial ships to military purposes, which will be distributed throughout the Diaspora Sector while waiving the normal architecture fee. Imperium wide mercantile shipping hull percentages dropped by 14% due to casualties during the fighting between factions in rebellion.
1126
Norris manages to make peace with the Aslan and turns his fleets toward the Vargr menance of the Kforuzeng.
The Aslan participate as allies in the operation.
1127
Gagushilaag is forced to abandon its starport.
The Ecclesiasty of Narquel is founded in Diaspora.
The Cumberan Confederation is founded in Diaspora.
Uneshuu is taken over by a band of corsairs, formerly Lucan's Imperium naval forces.
Earluiloiw settled by Hlyueawi, an Aslan clan and becomes their capital.
Six Gun's Colonial Army, returning after serving in Daibei, overthrow the world government and install themselves as rulers.
1128
Karroo was seized by a mercenary company built around a renegade Army platoon from Lucan’s Imperium.
1129
Pharoah's Plague, the massive release by the Garronean government of anti-Aslan chemical and biological agents on ihatei occupied worlds took place.
1130
The Vargr corsair group Kforuzeng, under assault from the Imperial fleet, loses their main base.
The Domain of Deneb, weary of fighting the Vargr, withdraw from Corridor, leaving it to the Vargr to plunder.
The Federation of Garrone completes their program of anti-Aslan biological warfare against their worlds invaded by ihatei. While successful in allowing the Garrone to reclaim their invaded worlds, the political and ecological backlash was severe.
And I see the years following being filled with entire systems tired of war making alliances of defense and trade which will possibly permanently split the 3I and leave a much smaller 4I.
Major Political Groups:
Regency of Deneb/Spinward Marches.
Zru sirkaa
Vargr Extents
Vilani Empire.
League of Antares
Gateway Protectorate
3I/4I (Core)
Grand Duchy of Wenly Ruu
Federation of Ilelish
Delphine Empire
Federation of Deabei
Glimmerift Federation
Old Expanses Commonwealth
Solomani Confederation