A strategic plan based on the over-all situation of both belligerents is... more stable, but it too is applicable only in a given strategic stage and has to be changed when the war moves towards a new stage.... [Conversely, tactical plans may]... have to be changed several times a day.
Selected Works of Mao Tse-Tung (ed. Pergamon, 1965) - ISBN: 9780080229812