If they fail to return in time then even their combined might would not be enough for the state. Terrible times have approached in Terra, stories such as Shadows of Treachery and Praetorian of Dorn might not look up to the level of this story at this stage.
This is not only neatly written by the author but it also has the ticking of clock situation in which time is continuously running out. Everyone is on his heels all the time because the battle can turn in favor of any side at the end of the story.