Marshals NEED to co-operate well under these conditions, which frankly is one place you can have problems. People will follow a Generals Order were they may argue with and debate against a Marshal. But like Tom says, a realm that can't pull their !@#$ together deserves to take some knocks, just like a realm that has Marshals working against the General would have
I don't understand this. Just as I, humble troop leader, click the travel button confidently because I know my fellow nobles will do the same having received the order from the marshal without waiting them to read it, I, when one of the marshals, can confidently order my army to attack because I know the other marshals will do the same, having heard it from the General.
The army works fine because there is a single person which commands a bunch of people on a similar hierarchical level that would otherwise waste ages arguing. Marshal over nobles, General over Marshals.
I can agree that if a realm can't pull it together the moment a General is not around it deserves a beating. But the purpose of the game should not be to make this whole process harder by removing useful tools.
This does not meant the General should micromanage but that when the situation requires it, namely when different armies collaborate closely, he should have the tools to perform his task as chief of the entire armed forces. Because that's what he is tasked with: to make the war machine efficient and well oiled, and if that needs a sudden order to be done, well, be it.
This said, I still believe every general should be instructed by the ruler that his position is first and foremost a political one, the term minister of war being pretty fitting, such as assuring gold flows from the rich to the troops, dealing with allies, keeping nobles motivated and so forth. But it's not by removing the chance to act as leader of the Marshals that the latter side of the general's play gets developed.