Since Palpatine wanted to flip the table, he had to have sufficient justification.
Although most of what politicians said was empty talk, something like proclaiming oneself Emperor still required sufficiently convincing proof that one's own way was the right one.
Otherwise, Palpatine had suffered defeat after defeat on the battlefield, then turned around and claimed that he alone was the Galactic Republic's only way forward. Who would believe that?
In the original storyline, Palpatine still controlled Count Dooku. He induced Anakin Skywalker to kill Dooku, then killed the leaders of the five major corporate giants, including San Hill and Nute Gunray, ending the war within a few days. That was naturally an extraordinary achievement.
But what about now? Count Dooku had long since seen through his scheme under Tang Xiao's influence and simply gone off on his own. Among the five major corporate giants, San Hill and Nute Gunray had also become Tang Xiao's allies. The Corporate Alliance was trembling in fear, the Trade Federation had been carved up outright, and the grass on Shu Mai's grave was already two meters tall.
The last one, the Technological Alliance, was secretly colluding with the Galactic Republic. But under the current circumstances, how could they possibly make a move against the Technological Alliance? They did not have enough time to win it over.
The Galactic Republic had achieved quite a few victories against the Confederacy of Independent Systems. During the previous counteroffensive, they had cleared out a large portion of the Northeastern Territory. On the Eastern Territory front, they had also liberated all the Mid Rim Territories that the Confederacy of Independent Systems had captured during the first two years of the war. They were now besieging Saleucami Planet, a key world leading into the Confederacy's ruling core.
But in the Duchy