The less the men are "worried" by unnecessarily harsh treatment, absurd and cruel restrictions, curtailment of natural rights, the better they act, the easier they are liable to reform and make good.
Dr.Musgrove to his _Nervous Breakdowns_, tells a story of two commanders which well illustrates this point: In a certain war two companies of men had to march an equal distance in order to meet at a particular spot.

The one arrived in perfect order, and with few signs of exhaustion, although the march had been an arduous one.

The other company reached the place utterly done up and disorganised.

It was all a question of leadership; the captain of the first company had known his way and kept his men in good order, while the captain of the second company had never been sure of himself, and had harassed his subordinates with a constant succession of orders and counter-orders, until they had hardly known whether they were on their heads or their heels.

That was why they arrived completely demoralised.
In war, as in peace, it is not work that kills so much as worry.
A general may make his soldiers work to the point of exhaustion as Napoleon often did, yet have their almost adoring worship.