Helmuth von Moltke the Elder Quote

The tactical result of an engagement forms the base for new strategic decisions because victory or defeat in a battle changes the situation to such a degree that no human acumen is able to see beyond the first battle. In this sense one should understand Napoleon's saying: "I have never had a plan of operations."
Therefore no plan of operations extends with any certainty beyond the first contact with the main hostile force.

"On Strategy" (1871), as translated in Moltke on the Art of War: Selected Writings (1993) by Daniel J. Hughes and Harry Bell, p. 92