It's not that they want to harm their allies, but once the Allied Forces can't hold on and actively seek assistance, the Iris can take control of the Alliance.
Moreover, Iris also needs to see a complete break between the Alliance Army and other Southern Continent nobles.
After all, from the beginning, the cooperation between the Alliance Army and the Iris Legion was never the only choice; there were many lords in the Southern Continent capable of developing the Old Continent, comparable to Iris, with several contenders.
For example, the Duke Simon's Mansion.
Only when the Allied Forces thoroughly eliminate the Duke Simon's Mansion, their alliance would be firm enough.
If Duke Simon is really to be killed, it would offend a large noble class in the Southern Continent.
Such an Alliance Army would have almost no choice but to collaborate with the Iris.
