During the Three Kingdoms period, after a military defeat, Liu Bei sought refuge with Yuan Shao in Hebei. One day, Liu Bei asked Yuan Shao's officer Chen Zhen to deliver a letter to Guan Yu, who was still in Cao Cao's camp. Upon learning Liu Bei's exact whereabouts, Guan Yu prepared to bid farewell to Cao Cao and set out from Xuchang in Henan, escorting Liu Bei's two wives to reunite with him.
When Cao Cao learned of Guan Yu's intentions, he repeatedly avoided meeting him. Unable to do otherwise, Guan Yu wrote a letter of farewell to Cao Cao, leaving behind the gold, silver, and other gifts Cao Cao had previously bestowed upon him, along with the official seal of "Marquis of Hanshou Pavilion." He departed taking only his original followers and personal luggage.
When Cao Cao learned that Guan Yu was leaving, he personally led his officers and soldiers to pursue him and urged him to stay. Guan Yu replied, "I came to bid you farewell several times but was never granted an audience, so I had no choice but to leave a letter. I have left behind all the gold, silver, and treasures you bestowed upon me, as well as your official seal." Cao Cao said, "I feared you might not have enough money for the journey, so I have brought a tray of gold for you." Guan Yu declined, asking Cao Cao to keep the gold to reward his troops. With no other option, Cao Cao ordered an officer to present a brocade robe with both hands, asking Guan Yu to keep it as a memento. Suspecting a trap, Guan Yu did not dismount to accept it; instead, he used the tip of his Green Dragon Crescent Blade to lift the robe and drape it over his shoulders, then thanked Cao Cao and rode away.
Since Guan Yu lacked the travel permit signed by Prime Minister Cao Cao, he was pursued and intercepted by Cao's generals along the way. At Dongling Pass, General Kong Xiu demanded Guan Yu produce the prime minister's clearance, threatening to hold his family hostage otherwise. Enraged, Guan Yu raised his bronze blade and charged at Kong Xiu, leaving the general dead beneath his horse.
When Guan Yu passed through Luoyang, Governor Han Fu urgently gathered his officers. The deputy general Meng Tan argued, "Guan Yu is unmatched in bravery and cannot be defeated by force—we must capture him through strategy." After setting their plan, Han Fu himself strung his bow and led a thousand men to guard the pass. Meng Tan rode out with twin swords to challenge Guan Yu, but after just three exchanges, he turned his horse and fled, intending to lure Guan Yu into a trap. However, Guan Yu's horse was so swift that he caught up in an instant, raised his great blade, and cleaved Meng Tan in two. Han Fu, hiding by the gate, then shot a hidden arrow that struck Guan Yu in the left arm. Enraged, Guan Yu pulled the arrow out with his teeth, blood streaming, and charged straight at Han Fu, cutting him down with a single stroke that split his head and shoulder.
Fearing further ambushes along the road, Guan Yu fled through the night toward the water pass. The pass commander, Bian Xi, hid over two hundred armed assassins in Zhenguo Temple, planning to lure Guan Yu inside and kill him. However, a monk named Pu Jing, a fellow townsman of Guan Yu, learned of the plot and secretly warned him. "Beware, general—Bian Xi means to murder you here," Pu Jing whispered. Forewarned, Guan Yu struck first, splitting Bian Xi in two with a single blow of his blade.
Guan Yu pressed on toward Xingyang. Prefect Wang Zhi, who was close kin with the slain Han Fu, outwardly fawned over Guan Yu while secretly plotting with his subordinate Hu Ban to surround Guan Yu's lodgings with a thousand soldiers, each holding a torch, and burn him alive at the third watch. But Hu Ban, moved by Guan Yu's noble character, secretly revealed Wang Zhi's deadly scheme. Startled, Guan Yu fled that very night. Wang Zhi, galloping after him with leveled spear, was met by Guan Yu's blade and cut in two at the waist.
As Guan Yu journeyed, he arrived at the border of Huazhou, where the defending officer Liu Yan came out to greet him. Guan Yu requested a boat to cross the Yellow River, but Liu Yan, fearing the wrath of Xiahou Dun and his subordinate Qin Qi, refused. Forced to find his own way, Guan Yu reached the ferry crossing, where Qin Qi demanded to see the travel pass issued by Cao Cao. Enraged by this obstruction, Guan Yu raised his blade, and in one swift stroke, Qin Qi's head fell to the ground.
Guan Yu passed through five strategic passes under Cao Cao's control, slaying six enemy generals, and finally reunited with Liu Bei.
Later generations summarized this story into the idiom "Passing Five Gates and Slaying Six Generals," which metaphorically means overcoming numerous obstacles and difficulties to finally achieve one's goal.
Source: *Romance of the Three Kingdoms*
Meaning of the Idiom: Later, the Chinese idiom "过五关斩六将" came to describe overcoming numerous obstacles and difficulties to finally achieve one's goal.