The already mentioned Preparation for War and Command of War.
In the preparation everyone participates, it's a task, a duty, a responsibility.
The command is done by only one person. Optimally The Statesman and the Commander is one person, if this isn't possible the divided roles need one-one persons.
Many tried to unify these roles, but failed, due to the roles weren't unison. Examples are Alexander the Great, Hannibal, Julius Caesar, Gustav Adolph, Frederick the Great, Napoleon. They tried alone, but they couldn't implement their goals with the community, the construct was depended on their authority, prestige, and after their death it crumbled.
An ideal pair was Bismarck and Moltke.
An ideal individual is Hitler. [Well others might think otherwise, but this was written in early 1943. - Bernd]