Upon learning that the Rebel Alliance has taken the bait regarding the trap at Endor of the Death Star II plans, Emperor Palpatine departed from the Imperial Center on his personal C-3 passenger liner, the Excalibur to head over to a Super Star Destroyer that would take him to Endor. During the trek, where he was escorted by the TIE Advanced x1 , the Excalibur ended up ambushed by Zaarin's forces, composed of the Assassin-class corvette Ram and at least two Assault Gunboats. Upon ambushing the Excalibur, Zaarin's forces had been notified via radio transmissions, with a large attack group composed of several of his best forces en-route to the Excaliburs position. Because neither Alpha Squadron nor re capable of holding off the attack by themselves, as well as the vital importance of ensuring the Emperor's survival/escape in terms of the Empire's survival, the TIE pilot and Emperor's Hand, Colonel Maarek Stele, leading the TIE Advanced x1 Delta Squadron with his Missile Boat, Tau 1, were dispatched to supply reinforcements to the Excalibur.
Afterwards, the Emperor was returned to Coruscant. Although the Emperor, and by extension, the Empire itself, was safe at the moment, Imperial Intelligence, doing its investigation on the ambush, confirmed that the Assault Gunboats used to ambush the Emperor were part of the Emperor's special reserve forces, meaning that Zaarin still had forces deep within the Imperial hierarchy.
Palpatine later met with Grand Admiral Thrawn regarding the progress of the battle, with the latter stating he currently had a trap laying in wait for Zaarin.
The second wave's content will vary depending on what happens to the two Assault Gunboats.
- If Z-Mu 1 is destroyed first then the attack consists of Assault Gunboats, which will attack the Liner, while TIE Avengers will attempt to divert the escorts away.
- If Z-Mu 2 is destroyed first then the attack consists of at least 9 additional Assassin-class corvettes as well as Assault Gunboats.
- If both were destroyed simultaneously then the Frigate Kimik will stay put and launch TIE/sa bombers, to attack the Liner and TIE Avengers to attack the escorts.