A philosopher would say this is in part this is a factual question relating to success so one approach
would be to study the methods of a great general such as Napoleon. Tolstoy did this and from his
novel War and PeaceI remember, for instance, that Napoleon was great because he was a strategist
rather than a tactician. He took a long term view of how things would develop, rather than waiting to
react to actual occurrences.
It also might be an ethical question, and the paper "Ethics and Public Office" in Mortal Questionsby
Thomas Nagel might give you some guidance as to the ethical issue involved. You might also
consider what makes a good general in the wider context of when? In the past, when the general
was on the battlefield, now when there is less need for soldiers, or in the future when fighting at
ground level or in the air no longer takes place. You might look at Hannah Arendt's book On Violence
to help you consider the nature of force, authority and violence.