The first punch to the chest was met with a step forward, the second and third to the face with a raising of the chin. The fourth, then fifth appeared to knock him unconscious.

But, getting to his feet, and with his hands kept firmly behind his back, he faced down his assailant again, and again, and again, a symbol of what has largely been peaceful opposition against an increasingly authoritarian power.

The assailant appeared to take exception to one of the many “Lennon Walls” in Hong Kong, which is in the grip of unprecedented political unrest against the erosion of civil rights in the semi-autonomous region of China.

The walls, which have started appearing across the city in recent weeks, are plastered with colourful notes protesting an extradition bill declared “dead” by the government but still not officially withdrawn.

The video was shared earlier this week by Edith Leung, a member of staff at the Democratic Party of Hong Kong, a centre-left party and the third largest in the Legislative Council.

Aftermath of protesters storming Hong Kong government HQ: In pictures Show all 15 1 /15 Aftermath of protesters storming Hong Kong government HQ: In pictures Aftermath of protesters storming Hong Kong government HQ: In pictures The lobby of the Legislative Council building in Hong Kong is seen covered in graffiti after it was stormed by protesters Getty Aftermath of protesters storming Hong Kong government HQ: In pictures Police officers stand guard at the Legislative Council building in Hong Kong after it was stormed by protesters EPA Aftermath of protesters storming Hong Kong government HQ: In pictures The colonial flag of Hong Kong hangs in the chamber of the Legislative Council after protesters stormed the building Reuters Aftermath of protesters storming Hong Kong government HQ: In pictures Police officers are seen behind cracked glass panels that were damaged by protesters trying to ram their way into the Legislative Council building EPA Aftermath of protesters storming Hong Kong government HQ: In pictures Shattered glass is seen on the outside wall of the Legislative Council of Hong Kong after protesters smashed their way in the building AP Aftermath of protesters storming Hong Kong government HQ: In pictures Riot police patrol the Legislative Council building in Hong Kong after it was stormed by protesters Getty Aftermath of protesters storming Hong Kong government HQ: In pictures Police officers inspect damage to the Legislative Council building in Hong Kong after it was stormed by protesters AFP/Getty Aftermath of protesters storming Hong Kong government HQ: In pictures A caricature of Hong Kong leader Carrie Lam is pasted on a pillar outside of the Legislative Council after protesters broke into the building Reuters Aftermath of protesters storming Hong Kong government HQ: In pictures Graffiti is seen in the chamber of the Legislative Council in Hong Kong after protesters stormed the building Getty Aftermath of protesters storming Hong Kong government HQ: In pictures Abandoned placards and litter is seen outside the Legislative Council building in Hong Kong after a protest on July 1 EPA Aftermath of protesters storming Hong Kong government HQ: In pictures A painting hung i the Legislative Council in Hong Kong is covered in graffiti after protesters stormed the building Getty Aftermath of protesters storming Hong Kong government HQ: In pictures A lift in the Legislative Council building is seen covered in graffiti and litter after protesters stormed the building Getty Aftermath of protesters storming Hong Kong government HQ: In pictures The chamber of the Legislative Council in Hong Kong after protesters stormed the building Getty Aftermath of protesters storming Hong Kong government HQ: In pictures A desk in the chamber of the Legislative Council in Hong Kong is covered in graffiti after protesters stormed the building AFP/Getty Aftermath of protesters storming Hong Kong government HQ: In pictures An area inside the Legislative Council building complex is strewn with litter and smashed glass after it was stormed by protesters Getty

It shows a man repeatedly punched by an older man, who later tears down dozens of the notes plastered to a wall in Kowloon Bay.

A number of people watched as he was later led away by police.

“What the hell is happening? This is insane!” Ms Leung wrote, before later appealing on behalf of the victim’s uncle for witnesses.

Ray Chan, a former Hong Kong parliamentarian, tweeted: “In Hong Kong, pro-Cops & pro-China thugs are just around the corner in your neighborhood. The young man showed real courage and wisdom as he defended the Lennon Wall.”

Hong Kong human rights campaigner Johnson Yeung described the video as “painful to watch”.

“I salute the young person who didn't fight back nor back off from violence. He was hit 13 times by pro-Beijing fellow in the face, and he didn't fight back,” he said.

Young people have been at the forefront of huge rallies in recent weeks against the extradition bill, which would have allowed those suspected of crimes to be sent to mainland China for trial.

Activists have vowed to keep up the pressure until Hong Kong leader Carrie Lam officially withdraws the bill. Many are also demanding her resignation.

Wang Zhimin, the Chinese government's chief representative in Hong Kong, said that the central government in Beijing firmly supported Ms Lam.

Dismissing calls to exonerate protesters who have been arrested, he said it would be "a blatant challenge to the rule of law in Hong Kong."

"Regarding the recent series of violent incidents, all Hong Kong people, including those present, have expressed condemnation," he said in a speech to Beijing loyalists in Hong Kong.

The protests against the proposed extradition legislation have given voice to fears that Hong Kong is losing the freedoms guaranteed to it when the former British colony was returned to China in 1997.

Extradition bill 'is dead' says Hong Kong leader Carrie Lam

Critics fear suspects would face unfair and politicized trials in mainland China, and that critics of the ruling Communist Party would be targeted.

On 1 July, the 22nd anniversary of Hong Kong's handover from Britain back to China, a peaceful march drew hundreds of thousands of people but was overshadowed by an assault on the territory's legislative building.

A few hundred demonstrators ransacked the building, spray-painting slogans on the chamber walls, overturning furniture and damaging electronic voting and fire prevention systems.

Tens of thousands of people joined the most recent rally on Sunday, seeking to carry their protest message to those in the mainland where state-run media have not covered the protests widely.