Attack the enemy before he is ready

Attack the enemy before he is ready is a maxim Kong Ming invokes to explain the decisive advantage of acting before an opponent can prepare. Its clearest statement comes during the crisis of Meng Da’s rebellion: Kong Ming predicts that Sima Yi will move before Meng Da expects, and Sima’s swift attack confirms the warning. Elsewhere, the same principle informs campaigns and stratagems built around supply shortages, concealed forces, diversion, and the deliberate delay of an enemy’s response.

The Maxim and Its Application

When Meng Da receives Kong Ming’s warning to strengthen his defenses, he dismisses the danger. He believes Sima Yi is too far away to reach him for at least a month, leaving ample time to repair the defenses. Kong Ming rejects that calculation, quoting the Art of War maxim: “Attack the enemy before he is ready; do what no one expects.” The point is not simply to attack quickly; it is to recognize that an opponent’s expected timetable may itself be a vulnerability.

Sima Yi acts on precisely that opening. Rather than wait for orders or continue toward Chang’an as instructed, he immediately marches against Meng Da, joining forces with Xu Huang on the way. He also learns that Kong Ming has tried to warn Meng Da and acknowledges Kong Ming’s judgment. Meng Da, meanwhile, is being delayed by neighboring governors while he waits for their support. Sima Yi conceals his knowledge of the planned rebellion, sends Meng Da a message that implies he is still a loyal Wei commander marching toward Chang’an, and arrives before Meng Da is ready. The maxim thus connects intelligence, speed, and deception: the attack succeeds because the intended target misreads both the attacker’s location and the time available to prepare.

Speed, Supplies, and the Opponent’s Assumptions

The principle also appears in Cao Cao’s advance against Yuan Shao at Guandu. Yuan Shao commands a vastly larger army, while Cao Cao can muster only about one-tenth as many troops. Cao Cao’s adviser Xun You warns that their supplies are limited and would soon run out if the campaign became prolonged; he therefore urges an immediate attack. Cao Cao agrees and advances. Here, acting before the enemy is ready is inseparable from acting before one’s own supply constraints become decisive. Delay would favor the larger army; an early offensive offers a chance to contest that advantage.

At Nanyang, Jia Xu applies a related logic by reading Cao Cao’s apparent preparations rather than accepting them at face value. He notices Cao Cao focusing attention on the southeastern wall, whose defenses are weak, while placing materials on the northwest side as though that were the intended point of attack. Jia Xu concludes that the display is a feint, designed to make the defenders misjudge where the assault will come. He advises Zhang Xiu to move elite troops out of sight near the southeastern wall and put ordinary people in armor on the northwest wall. The defense is designed to let Cao Cao commit to what he believes is an opportunity, then trap his forces after they breach the vulnerable section. The episode makes readiness a problem of interpretation as well as preparation: a commander can be misled by signs that seem to reveal an enemy’s plan.

Concealment and Coordinated Surprise

Kong Ming’s first test as Xuande’s adviser at Bowang turns the maxim into a coordinated plan of concealment and timed action. He positions Guan Yu in the hills around Bowang, with orders to let the invading force pass and attack its rear and supply train when flames rise. Zhang Fei is to hide in the valleys and strike the enemy stores. Other commanders prepare fires beside the ravine through which the enemy must advance, while Zhao Zilong leads the advance party and is instructed to pretend to retreat when he encounters Cao Cao’s men. The several detachments are not to reveal their roles at once: the plan depends on drawing the enemy forward and making the signal of fire the cue for an attack from different directions.

A later plan at Xi Wei Slope uses a similar device to unsettle a pursuing force. Mi Fang and Liu Feng are ordered to station troops under blue and red banners, then retreat in opposite directions when the enemy appears. Their apparent flight is meant to confuse the pursuers and delay them; once fires rise from Xinye, they are to prepare an ambush and then move to support the forces at the upper waters. The maneuver treats an enemy’s haste to pursue as something that can be manipulated. Rather than meeting the advance directly, the defenders create uncertainty about where the danger lies and when it will emerge.

During the retreat after the Sun–Liu alliance’s victory at Red Cliffs, Kong Ming again assigns forces to anticipated escape routes. He sends Zhao Zilong to ambush Cao Cao’s retreat through Wulin, ordering him to wait until half the force has passed before setting the undergrowth alight. Zhang Fei is sent to block the roads toward Yiling and attack when the enemy stops to prepare food. Kong Ming does not promise that either commander will capture Cao Cao; the stated aim is to inflict losses and assist the broader pursuit. These instructions rely on predicting the enemy’s next move and striking when the retreating force is occupied and divided.

Limits and Significance

Not every apparent lesson in readiness produces an advantage. At Jieting, Kong Ming’s orders are undermined when Ma Su rejects Wang Ping’s advice to defend the road and instead takes a position on a hill. Sima Yi advances, encouraged by the knowledge that Ma Su is inexperienced. Ma Su’s troops are cut off from water, begin to desert, and are forced to retreat; Sima Yi captures the city. The episode contrasts preparation in theory with sound decisions on the ground. Ma Su cites military writing but fails to adapt his position to the immediate circumstances, while Sima Yi exploits the weakness as soon as he recognizes it.

Taken together, these episodes give the maxim a practical rather than merely abstract meaning. Acting before an opponent is ready may mean striking before supplies run low, arriving sooner than a rival anticipates, concealing the real point of attack, or exploiting a commander’s false confidence. Success depends on accurate judgment and coordinated timing; speed alone cannot rescue a plan built on a mistaken reading of terrain or circumstance. The repeated emphasis on surprise makes preparedness a contest of perception: the advantage belongs to the commander who understands what the opponent expects, and can act before that expectation has time to change.