The best scheme didn't actually need to be unnoticeable, with no clues left behind.
The best scheme simply needed to perform the "correct" move at a critical moment and then let everything else develop naturally.
"San Antonio is in utter chaos."
Any bystander, or even a child, would be able to come to such a conclusion right now.
The now deceased Maria's faction voluntarily reduced the amount of their territory by a great amount. They even gave up the Golden Plains, which was the #1 food producing region in the entire land of Eich, the most precious land in all of San Antonio.
Duke Barrot took command of Maria's faction. He was the one who gave the order to abandon their own territory in order to improve their defense lines. In just a short two weeks, he mysteriously came to some sort of agreement with the demons and ogres in the Saffey Mountains, reaching a ceasefire on the frontlines here.