Wu Song (), also known as Second Brother Wu (), is a legendary folk hero recounted since the 13th century; and one of the well-known fictional characters in Water Margin, one of the Classic Chinese Novels.

Nicknamed "Pilgrim", he ranks 14th among the 36 Heavenly Spirits of the 108 Heroes. In folktales derived from the novel, Wu Song is a martial arts student of Zhou Tong, specialising in chuojiao. In the novel, he fights well with bang (quarterstaff) or a pair of broadswords.

Attestations Legends surrounding the heroic figure of Wu Song have existed since the late Song dynasty. A "Pilgrim Wu" () is briefly mentioned in the 13th-century collection Stories Told by an Old Drunkard () by Luo Ye (). The earliest record of a tale in which Wu Song fights a tiger comes from a zaju play written by a late-13th-century writer who wrote under the pen name "Red-Tattooed Second Li" (), but the play itself is no longer extant. The oldest surviving Chinese drama version of the tiger-slaying episode is the chuanqi or "miraculous" play by Shen Jing (, 1553-1610) dating to the late 16th century, and the earliest editions of Water Margin that contain the tiger-fighting story also date around the end of the 16th century.

In Water Margin Background A native of Qinghe County, Hebei, Wu Song is described in Water Margin as a tall, good-looking and muscular man with shining eyes and thick eyebrows. As his parents died early, he was raised by his dwarf elder brother Wu Dalang (; literally "Wu the Older"), whom he respects and loves very much. Wu Song's nickname "Wu Erlang" (literally "Wu the Second") is a reference to him being the second son.

On one occasion, Wu Song gets into a drunken brawl and knocks a man unconscious. Thinking that he has killed the man, he flees from home and takes shelter in the residence of the nobleman Chai Jin. There, he meets Song Jiang, who is on the run from the law after killing his mistress Yan Poxi. They become sworn brothers.

Slaying the tiger

Upon learning that the man he knocked out is not dead, Wu Song heads home and passes by an inn near Jingyang Ridge where he sees a banner reading "After Three Bowls, Do Not Cross the Ridge" (), and goes in for a break. The innkeeper explains that the inn's homebrewed alcoholic drink is so strong that customers usually get drunk after consuming three bowls and cannot cross the ridge ahead. Still sober after three bowls, Wu Song demands more. By the end of his meal, he has consumed 18 bowls but still looks steady. He is about to leave when the innkeeper stops him and warns him about a fierce tiger on the ridge. Wu Song suspects that the innkeeper is trying to scare him into spending the night at the inn. Ignoring the advice, he continues his journey, armed with only a quarterstaff.

As he approaches the ridge, Wu Song spots an official notice warning travellers about the tiger. To avoid losing face, he presses on and starts feeling the effects of alcohol, so he takes a nap on a large rock. As he is resting, the tiger leaps out of the woods and shocks him out of his stupor. After narrowly dodging the tiger's first three charges, Wu Song attempts to fight back but breaks his quarterstaff on a tree. Unarmed, he musters all his strength and manages to pin the tiger face down in a pit with his arms, raining blows on its head with his bare fists. After punching the tiger unconscious, he picks up his broken quarterstaff and keeps hitting the tiger until he is sure that it is dead. Exhausted, he leaves the spot after a short break and encounters some local hunters, who are amazed at his incredible feat. Impressed, the local magistrate of the nearby Yanggu County offers him the job of a chief constable. Wu Song accepts and settles in the county, where he unexpectedly meets his brother Wu Dalang, who has moved to Yanggu from Qinghe.

According to some narrations in Yangzhou storytelling, particularly the "Wang school", Wu Song's slaying of the tiger took place "in the middle of the tenth (lunar) month" of the "Xuanhe year ".

Avenging his brother

Wu Dalang takes Wu Song home and introduces him to his wife Pan Jinlian, who was originally a rich man's servant and had been forced to marry Wu Dalang – the ugliest man in town – as punishment for resisting her master's sexual advances. Wu Song also learns that the couple has moved to Yanggu to avoid harassment by their neighbours back in Qinghe: they called Wu Dalang, who sold shaobing for a living, "Three-Inch Nail Tree Bark" () for his stature, and mocked him even more after his marriage as he looks starkly incompatible with his younger, pretty wife. After meeting Wu Song, Pan Jinlian is immediately attracted to her handsome, well-built brother-in-law, but Wu Song sternly spurns her attempt to seduce him.

The magistrate later sends Wu Song on an assignment to escort funds to the capital Dongjing (; present-day Kaifeng, Henan). When Wu Song returns home two months later, he is shocked to learn that his brother had died and his body had already been cremated. Not believing Pan Jinlian's account that Wu Dalang had succumbed to a sudden illness, Wu Song privately conducts an investigation and learns that Pan is having an affair with Ximen Qing, a wealthy gentry man who has seduced her with the help of the teahouse owner Granny Wang, who lives next door. Tipped off by their neighbours, Wu Dalang had caught his wife and Ximen Qing in bed together, but Ximen had kicked him so hard in the abdomen that it had left him bedridden. Later on, Ximen Qing, Pan Jinlian and Granny Wang had conspired to murder Wu Dalang by poisoning his medicine, and then Ximen had bribed the magistrate to close the case quickly and cremate the body. Wu Song finds the coroner, who had secretly kept a darkened bone as evidence of poisoning, and goes to the magistrate to plead his case, taking along with him some witnesses. However, the magistrate, having been bribed by Ximen Qing, dismisses Wu Song's plea on the grounds of insufficient evidence.

Denied legal avenue, Wu Song takes matters into his own hands. He invites their neighbours, including Granny Wang, to a belated wake for his brother. At the wake, he forces Pan Jinlian at knife-point to confess to the murder before decapitating and disembowelling her in front of everyone. Next, he makes the fear-stricken Granny Wang sign a confession in front of the witnesses. After that, he makes his way to Lion Restaurant () to confront Ximen Qing and kills him after a fight. Having avenged his brother, he goes to the county office to surrender himself.

As the locals are sympathetic to Wu Song, they plead for leniency on his behalf, so Wu Song gets spared the death penalty and ends up being sentenced to face-tattooing and exile in Mengzhou.

Meeting Sun Erniang and Zhang Qing

On the way to Mengzhou, Wu Song and the two guards escorting him pass by Cross Slope (; in present-day Fan County, Henan), where they take a rest in Sun Erniang's inn. Wu Song senses that Sun Erniang is up to no good and suspects that the alcoholic drinks served to them have been spiked with menghanyao (), a drug that causes unconsciousness. He pretends to be knocked out after consuming the drink. When Sun Erniang tries to lift him, he gets up and easily overpowers her in a fight. Sun Erniang's husband, Zhang Qing, comes home in time and stops the fight. Upon learning who he is, the couple apologises to Wu Song and treats him hospitably before seeing him off with his escorts to Mengzhou.

Life in Mengzhou At the prison in Mengzhou, Wu Song meets the warden and learns that all inmates are subject to a mandatory flogging called "100 strokes of shaweibang" (; "ego-killing staff") upon arrival. Just as he is about to be beaten, the warden's son Shi En speaks up and says that Wu Song looks pallid and might be ill, so the flogging is postponed. Over the next few days, Wu Song is surprisingly treated well in prison. He soon learns that Shi En is behind all this because he needs Wu Song's help in dealing with a hooligan called Jiang Zhong, nicknamed "Jiang the Door God". Shi En owns a restaurant called Happy Forest (), which has been seized from him by Jiang Zhong.

Agreeing to help Shi En to repay his kindness, Wu Song goes to confront Jiang Zhong at Happy Forest. Along the way, he drinks three bowls of alcoholic drinks at every place which serves alcohol he comes across, and has already consumed an enormous amount of alcohol by the time he reaches Happy Forest. He provokes Jiang Zhong into a fight and soundly beats him with a set of martial arts moves called "Jade Circle Steps and Mandarin Ducks Kicks" (). Jiang Zhong is forced to apologise to Shi En, give up Happy Forest, and leave Mengzhou for good.

A humiliated Jiang Zhong secretly conspires with two corrupt officials in Mengzhou – Instructor Zhang and Inspector Zhang – to take revenge. Inspector Zhang pretends to be impressed with Wu Song's physical prowess and asks the prison warden to let Wu Song stay in his residence. During this time, Wu Song is framed for larceny and gets thrown back into prison, after which he is exiled to another location. Shi En warns him of danger before seeing him off. Indeed, Jiang Zhong and the corrupt officials have bribed the guards escorting Wu Song to murder him along the way. At Flying Cloud Pool (), the guards and some assassins attack Wu Song, but he breaks free of the cangue and defeats and kills all of them. After that, he returns to Mengzhou to confront Jiang Zhong, Instructor Zhang and Inspector Zhang, who are having a party at Mandarin Ducks Tower () to celebrate Wu Song's presumed death. Wu Song kills the three men and Inspector Zhang's entire family of 15, and signs off "The killer is Wu Song, the Tiger Slayer" on the wall before leaving.

Becoming an outlaw

After fleeing Mengzhou, Wu Song heads to Cross Slope to find Sun Erniang and Zhang Qing, who advise him to take shelter with the outlaw band at Mount Twin Dragons (). The couple helps Wu Song disguise himself as an untonsured Buddhist pilgrim following the dhūtaguṇa path to avoid being recognised since the authorities have put up wanted notices with his portrait in the vicinity. Wu Song changes his appearance after putting on a Buddhist robe, necklace of skulls, and headband, and letting down his hair to conceal the convict tattoo on his face. He also obtains a pair of broadswords, and is henceforth nicknamed "Pilgrim".

En route, Wu Song encounters and kills a villainous Taoist priest nicknamed "Flying Centipede" and saves a kidnapped woman. Next, he passes by an inn and gets into a brawl with Kong Liang, beating up the latter. Kong Liang seeks help from his brother Kong Ming; the brothers ambush Wu Song when he is drunk, tie him to a tree, and beat him up in revenge. Luckily for Wu Song, he is recognised by Song Jiang, who happens to be staying with the Kong brothers then. The Kong brothers then release Wu Song, apologise to him, and they become friends.

Wu Song finally reaches Mount Twin Dragons and joins the outlaw band there led by Lu Zhishen and Yang Zhi. The outlaws from Mount Twin Dragons, including Wu Song, ultimately join the larger outlaw band at Liangshan Marsh following the battle of Qingzhou between government forces and the Liangshan outlaws.

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