In all fighting, the direct method may be used for joining battle, but indirect methods will be needed in order to secure victory. In battle, there are not more than two methods of attack.. the direct and the indirect; yet these two in combination give rise to an endless series of maneuvers.
Sun Tzu, Julius Caesar, Einhard, Niccolò Machiavelli, Carl von Clausewitz (2016). “Strategy Six Pack”, p.14, Lulu.com