Have you ever read War and Peace by Lev Tolstoy? It's a great book with many stories wrapped up with History. It is based in Russia during the Napoleon era and, of course, it also tells about battles.
There is one thing in the Tolstoy's point of view that caused me some thinking. More or less, this is the reasoning of the author: most of the times, battles are not decided by generals or strategists but by single episodes of bravery or dastardliness in the troops.
Of course there is a part of truth in this but, as usual, life is slightly more complicated. A good commander should be able to understand if its soldiers are motivated, which are their strengths and their weaknesses. And a good commander always has an ace in the hole.
Victory and Fortune
Many great commanders in the past were undoubtedly lucky and often luck is considered an essential attribute of good strategist and I'm sure you have already heard that fortune favors the bold. But a commander that points everything on its luck is doomed to lose.
This is why, really great commanders always have some troops reserved for difficult moments (for example Napoleon had the Old Guard) and they know when engage a battle and when retire their troops.
For a manager it works the same. If he plans the team at one hundred percent of the time, there will no room for contingencies. If he accepts every job proposed by the salesmen, the risk is to provide a poor job or to miss deadlines. He can put its subordinates under pressure for some weeks but not forever.
Sometimes managers have to take some risk and they can be lucky, but fortune doesn't lasts forever.
Image taken from Wikimedia Commons (public domain)