1 Hour After the Battle of Endor (4 ABY)
Darth Vader takes a shuttle to Coruscant, to gain control of the Imperial Government and declare himself Emperor. Admiral Piett is given command of the Executor and Death Squadron, and given order to slow the invading outsiders but to avoid a major engagement. Meanwhile, he issues an order to Grand Moff Ardus Kaine to gather all ships in Oversector Outer at Eriadu, the center of Imperial Power in the Outer Rim.
1 Week After Endor
Darth Vader arrives at Coruscant. Despite his order for silence on what occurred at Endor, news had gotten out over the Emperors death. Along with causing unrest in the civilian population, the news made many high ranking officials appointed by Palpatine fear that Vader intended to replace them. Among them was Director of Imperial Intelligence Ysanne Isard. An ambitious favorite of Palpatine known for eliminating her way to promotion, Isard correctly guessed that she would be purged or sidelined by Vader, and decided to have the Sith Lord preemptively assassinated.
After having her agents kidnap Imperial Grand Vizier Sate Pestage, she had a bomb surgically implanted in him and had her brainwashing experts remove any memory of the experience. The bomb was set to detonate when Pestage and Vader were in a private meeting, however Vader sensed danger when entering the room and force pushed Pestage away. This bomb detonated a moment later, killing Pestage but leaving Vader unhurt. The unique method of assassination made it clear that Isard was behind the attempt, forcing her to flee Coruscant on her Super Star Destroyer the Lusankya, which was hidden below the planet's surface. Fleeing to the outer rim, the incident killed millions and ended any hope of Vader inheriting a unified Empire.
1 Month After Endor
Isard and Lusankya arrive on Kamino, taking control of the critical system and its cloning facilities just as the Empire needs new soldiers the most.
Vader leaves Coruscant to lead the war effort on the Executor once again.
2 Months After Endor
The wider galaxy learns that Boba Fett's reported death on Tatooine during the rescue of Han Solo was premature, after he is seen on Mandalore.
4 Months After Endor
Unknown to the wider Galaxy, the Human Trader State (HTS), the more Xenophobic and Militant group of Traders, venture into the Unknown Regions and intrude into the territory of the Chiss Ascendancy, triggering the Chiss-Trader War.
5 Months After Endor
Rumors circulate of a meeting between the Rebels and the Triple Alliance on the recently fallen planet of Javin.
6 Months after Endor
Sleeper Agents of the Orthodox Unity begin to infiltrate areas of Triple Alliance and Imperial rule. They proceed to begin converting the native populations to join the unity, while providing intelligence to their migration fleet, which is beginning an unprecedented maneuver of traveling the Galaxy below the galactic disk, where they plan to emerge on the less defended opposite side of the Empire.
7 Months after Endor
Emissaries from the Chiss approach Grand Admiral Thrawn, requesting Imperial Assistance against the Human Trader State.
8-9 Months after Endor
The Battle of Eriadu, the largest battle in Galactic History, occurs. Perhaps more accurately called the Eriadu campaign, this 37 day engagement throughout the Eriadu sector saw the entirety of the Triple Alliance fleet engage the combined forces of Death Squadron under the command of Darth Vader on the Executor, 80% of the forces assigned to Oversector Outer (the Outer Rim) under Grand Moff Ardus Kaine on the Reaper, part of Azure Hammer Command commanded by Grand Admiral Osvald Teshik on the Super Star Destroyer Whelm, and the recently completed Super Star Destroyer Annihilator commanded by Admiral Gaarn.
The first two weeks of the battle saw the Empire inflict greater casualties on the Triple Alliance, including the destruction of an Ankylon class titan. However, things began to deteriorate after the Vasari Independent Republic finished constructing a weapon not yet seen in the conflict, Orkulus-class Starbases equipped with phase drives, which proved deadly against the Empire's smaller ships. The turning point occured on day 23, when Grand Admiral Teshik's forces were ambushed by several Orkulus starbases and a Kultorask titan. With his smaller ships picked off and the Whelm reduced to 19km long burning mass of metal after a 6 hour engagement, Teshik could do nothing but use his ship as a shield to cover the retreat of his remaining Star Destroyers. After giving the order to abandon ship, Teshik personally sets a course to ram the Kultorask titan right through the eye, destroying both ships.
On day 32, Darth Vader gave the order to evacuate Eriadu, with the remaining Imperial forces only in control of the day time portion of the planet. On the night side, the Imperial Army attempted to prevent the landing of enemy forces while evacuating civilians, but was eventually destroyed by orbital bombardment, making it clear to all that this war would be settled by control of space. By the time the last transports left on day 37, the space around Eriadu had become one of the largest debris fields in the galaxy, with both sides losing thousands of space ships. The Triple Alliance had sustained higher casualties overall, but in strategic terms the victory would have huge importance.
For while no one quite realized it at the time, the Empire's influence in the Outer Rim was at an end. Disillusioned with Darth Vader's approach at Eriadu, Grand Moff Ardus Kaine took the Reaper and the remnants of Oversector Outer to Bastion, informing Vader that he intended to reform the sector government there. In reality, he would create his own Empire there.
9 Months after Endor
With the Empire engaged at Eriadu, the Rebels liberate the key planet of Sullust on their own, making it the first permanent Rebel enclave.