The ordinary rule for use of military force is for the military command to receive the orders from the civilian authorities, then to gather and mass the troops, quartering them together.
Nothing is harder than armed struggle.
The difficulty of armed struggle is to make long distances near and make problems into advantages. Therefore you make their route a long one, luring them on in hopes of gain. When you set out after others and arrive before them, you know the strategy of making the distant near. Therefore armed struggle is considered profitable, and armed struggle is considered dangerous. To mobilize the whole army to struggle for advantage would take too long, yet to struggle for advantage with a stripped-down army results in a lack of equipment.