Sun Tzu, in his famous The Art of War, explains the rules and nuances of warfare, and one of his tenets is achieving momentum in battle:
In all kinds of warfare, the direct approach is used for attack, but the oblique is what achieves victory. A general who understands the use of the oblique has a source of tactics as inexhaustible as Heaven and Earth, which like the Rivers and the Oceans, will never run dry. Like the Sun and the Moon, they diminish and then replenish; they constantly renew themselves like the cycle of the Four Seasons.