From there the practice extended to generals. Before going to war it was advised that a general sit still. This is hinted at in the Sunzi, and I think is a source for the general reluctance to go to war found in his writing. Yes, I know people like to think this stuff came from hermits. Maybe that too.
There is something I find satisfying about imagining generals meditating before going into war. Confucius has a saying something to the effect of: While it is undeniable that a man who is not afraid of fighting tigers can be called courageous; If I had to follow someone into battle I would much prefer to follow a general who is afraid of tigers.