Yuan Shao and Cao Cao were childhood friends who knew each other inside out, but as adults, their rivalry for control of the realm turned them into sworn enemies.
Yuan Shao came from a powerful noble family, with five ancestors across four generations serving as the Three Excellencies; Cao Cao's background was far humbler, his grandfather being a eunuch. Initially, their common enemy was Dong Zhuo, who sought to depose the Han emperor and seize power. Yuan Shao fled Chang'an, raised troops in Bohai Commandery, declared himself General of Chariots and Cavalry, and became the leader of the rebel alliance. Cao Cao, commanding just a few thousand men, served under Yuan Shao as General Who Rouses Might.
When Dong Zhuo marched out of the pass to attack the coalition forces, Yuan Shao commanded over a hundred thousand troops but dared not engage. Cao Cao urged, "We raised the righteous army to punish tyranny. Now that the coalition is formed and Dong Zhuo has abandoned the safety of the pass to attack, we can defeat him in one battle and pacify the empire—this opportunity must not be lost!" Yet only Cao Cao led a few thousand men to face Dong Zhuo's general Xu Rong at Xingyang. Overwhelmed by superior numbers, Cao Cao suffered a crushing defeat, was struck by an arrow, and had his horse killed beneath him. He was saved only by his cousin Cao Hong, who rescued him and allowed him to escape with his life.
After Dong Zhuo's death, Cao Cao's power grew daily, and the Central Plains saw a struggle for supremacy between Yuan Shao and Cao Cao. Cao Cao's base was in Xuchang, while Yuan Shao appointed Tian Feng and Ju Shou as advisors, Yan Liang and Wen Chou as generals, selected one hundred thousand elite troops and ten thousand war horses, and prepared to attack Xuchang.
Liu Bei occupied Xuzhou and allied with Yuan Shao. Cao Cao marched east to attack Liu Bei, leaving Xuchang vulnerable. Tian Feng urged Yuan Shao to advance quickly. Yuan Shao said, "My son is ill. Let us wait until he recovers before launching the army." Tian Feng replied, "In times of war, to miss a golden opportunity over a child's illness—what a pity!"
When Cao Cao defeated Liu Bei, Yuan Shao finally led his army from Jizhou to Liyang on the Yellow River, sending Yan Liang as the vanguard to cross the river and fight. Ju Shou said, "Yan Liang is brave, but he lacks flexibility and should not be given independent command." Yuan Shao ignored this advice, and Yan Liang, encountering Cao Cao's main force, was killed in battle.
As Yuan Shao's generals Liu Bei and Wen Chou pursued Cao Cao's retreating army along the Yellow River, they were caught off guard at Yanjin when Cao's forces suddenly wheeled around and counterattacked, resulting in Wen Chou's death on the battlefield.
Cao Cao's army continued retreating to Guandu. Ju Shou added, "Our forces are numerous and well-supplied; though Cao's troops are fierce, they are few and running low on provisions. Cao's advantage lies in a swift battle, ours in a prolonged standoff. Now is not the time for a hasty advance."
Yuan Shao, ignoring the warnings of his advisors, clashed with Cao Cao at Guandu. After winning a few minor skirmishes, Yuan Shao turned to his strategist Ju Shou and boasted, "You advisors are always afraid to charge into battle. Before crossing the river, Tian Feng also warned me, saying Cao Cao was skilled in warfare and unpredictable, and that despite his smaller numbers, he should not be underestimated. But I have been through countless campaigns myself, and with my overwhelming numbers, I can crush him through sheer force. Now, haven't we proven victorious?"
Yuan Shao, relying on his old strategy that had defeated Gongsun Zan, built earthen mounds outside Cao Cao's camp, raining arrows down on Cao's troops from above, and dug tunnels straight into the enemy camp. Cao Cao, however, had prepared stone-throwing catapults, which launched massive boulders that crushed Yuan's archers atop the mounds. He also ordered deep trenches dug inside his camp, flooding them with water to drown Yuan's tunnels.
Ju Shou again proposed splitting forces to cut off Cao Cao's supply lines. Yuan Shao, trusting only his own mound and tunnel tactics, said, "Even Gongsun Zan couldn't withstand my attacks—what is Cao Cao to me?"
Cao Cao launched a surprise attack on Yuan Shao's supply lines, seizing and burning grain and weapons, leaving Yuan's army demoralized and scattered.
The Battle of Guandu ended with Yuan's army utterly defeated, and Ju Shou was captured alive by Cao's forces. After Yuan Shao returned to Jizhou, he said, "Tian Feng advised me, but I didn't listen. Now I return in great defeat—won't he laugh at me?" He then ordered Tian Feng executed.
"Change Without Fixed Pattern" originally referred to decision-making and actions that do not follow old conventions but embrace change. Now this idiom is not exclusively used for praise.
Source: *Records of the Three Kingdoms*, "Biography of Yuan Shao"
Meaning of the Idiom: Later, the Chinese idiom "变化无方" came to describe how decision-making and actions do not follow old conventions but embrace change.