To massively over simplify - one can see a repeating pattern in military leadership though out history.
This is particularly apparent in both of the World Wars and in the early years of the American Civil War.
Peacetime emphases and requires a different set of leadership skills then war. During times of calm, generals are forced to spend much of their time and effort on civil-military relationships. Strategy and policy are dominated by civilians. Officers are pressured into doing things by “the book” and often find themselves preparing to re-fight the last war.
But, when bullets start to fly, this rarely works. Armies that have become too rigid in applying doctrine and have overly focused on yesterday’s tactics, find themselves wasting lives and tasting defeat.
Wartime require a different leadership style. Combat is applied violence, and aggressiveness can be very difficult to control outside of conflict. But when the dogs of war are unleashed, battle rewards thoughtful, aggressive leaders who have the ability to inspire and think outside the box.
Hence a dilemma and a major source of early failure in many military forces. How do you keep the caged tiger’s claws sharp?