Definition
Winning without fighting is Sun Tzu's most famous and most quoted principle, articulated in Topic 3 of The Art of War: "the supreme art of war is to subdue the enemy without fighting." The deeper claim — easily missed — is the corollary: "Winning a hundred victories in a hundred battles is not the best possible outcome. Best is to subdue the enemy's troops without ever engaging them on the battlefield."
The principle establishes a hierarchy of attack: first attack the enemy's plans, then their alliances, then their army, and only as a last resort their fortified cities. The higher up the chain you can apply force, the less of it you have to apply — and the more whole the eventual victory.
Why it matters
How it works
The principle works by targeting causation as upstream as possible. By the time two armies are clashing on the battlefield, multiple opportunities to win without that clash have already been missed: the enemy's plans could have been spoiled before they were finalised, their alliances could have been broken before the campaign began, their morale could have been undermined before the march began.
The discipline is to ask, at every level of a contest, what would make the contest unnecessary? Not "how do I win this engagement?" but "how do I arrange conditions so this engagement does not have to happen?" The skilled strategist treats every fight as evidence of earlier failure — the failure to have arranged things such that the fight was already decided.
The principle is uncomfortable because it devalues the heroic narrative of victory. The best victories are unglamorous — there is no battle, no reversal, no dramatic story. Sun Tzu accepts this and even insists on it: "a victory that does not surpass the understanding of the vulgar crowd is not the best sort of victory."