Tuesday marks the 30th anniversary of the Tiananmen Square massacre — a bloody crackdown on a pro-democracy movement erased from history in China, but still remembered by the people who witnessed the chaos that swept Beijing.

Key points: Xiaoming Li is believed to be the first soldier to publicly share his experience of the massacre

Xiaoming Li is believed to be the first soldier to publicly share his experience of the massacre Estimates of the death toll have ranged from a few hundred to several thousand people

Estimates of the death toll have ranged from a few hundred to several thousand people Many people were jailed in a subsequent purge, while some fled China for Australia and the US

What had started as a relatively small gathering of students in mid-April 1989, swelled to more than 1 million by May 20 as ordinary citizens turned out to show their support for the protesters.

China's Government — which called the protest a "counter-revolutionary rebellion" — declared martial law that same day, mobilising more than 200,000 troops in the capital.

Among them was Xiaoming Li, a former People's Liberation Army soldier who said he never fired a shot was still wracked with guilt over the deaths of unarmed students and civilians when tanks rolled into Tiananmen Square on June 4.

Chinese students spent weeks camped out in Tiananmen Square campaigning for democracy. ( Reuters: Dominic Dudouble )

Mr Li, who came to Australia on a student visa in 2000 and now lives in Melbourne, was then a 25-year-old junior officer stationed in the north-eastern province of Liaoning when he received the orders to deploy on May 20.

"If I had not been in the army but had gone to school in Beijing, I would have been very likely to join the protests too, and may have been shot dead or injured by the soldiers," Mr Li told the ABC.

Mr Li is believed to be the first soldier to publicly confront the Chinese Communist Party's crackdown when he shared his story in 2002.

Thirty years on from the massacre, he wants to keep drawing the world's attention to the events of Tiananmen — in which estimates of the death toll have ranged from a few hundred to several thousand people.

Both Xiaoming Li and his sister, pictured with their parents in 1984, were members of the Chinese military. ( Supplied: Xiaoming Li )

'116th Division, where are you?'

On June 3, after spending 10 days waiting at a military base in eastern Beijing with the 39th Group's 116th Division, Mr Li said the Martial Law Troops Headquarters issued a chilling order.

"They ordered us to carry out martial law and arrive at Tiananmen Square on the morning of June 4 at all costs," he said.

Tens of thousands of civilians erected roadblocks in Beijing and crowded around military convoys to stop the vehicles from reaching the square in the city's centre.

Protesters surrounded army convoys as they tried to make their way to Tiananmen Square. ( Reuters: Ed Nachtrieb )

"When the soldiers unloaded bullets from the vehicle, and opened the boxes to hand them out, I saw faces in the small crowd [who had gathered] showing consternation, fear and disbelief. No one could even say a word," Mr Li said.

"I had the same fear, because as soldiers we knew that having guns and bullets meant people would die," he said.

Mr Li said his division commander, Feng Xu, told his soldiers it wasn't possible to receive orders because of an equipment failure, and the division lingered in Beijing's outer suburbs until late in the night of June 4.

"[But] I heard a clear cry over the radio: '116th Division, where are you?'" he said.

An eerie silence descended as the soldiers — increasingly scared and irritable as they remained trapped inside their vehicles for hours — heard the distant sound of gunfire.

"I didn't expect the People's Liberation Army to open fire on students and civilians in the 20th Century," Mr Li said.

Mr Li, fifth from the left, in Tiananmen Square on June 5, 1989, the day after the massacre. ( Supplied: Xiaoming Li )

'Fascist executioners'

Mr Li said his division didn't arrive at Tiananmen until 9:00am the day after the massacre, where they found the square cleared of students and replaced with soldiers.

As they entered central Beijing, Mr Li heard civilians calling them "fascist executioners", prompting at least one soldier in his vehicle to shoot in their direction.

Mr Li's military identification certificate, left, and commemorative medal, right, for his service during the martial law period were donated to the Immigration Museum in Melbourne. ( Supplied: Immigration Museum )

"Li Wei, the soldier beside me, fired several shots at the crowd on the highway interchange, and the falling bullet shells dropped on my body," he said.

"I shouted at him, 'stop shooting', but I don't know if anyone there died."

He described seeing tanks circling Tiananmen Square, as well as clothing riddled with bullet holes and stained with blood scattered in the square.

Mr Li and his fellow soldiers received a medal for their participation in the crackdown, but he said he did not fire a single shot.

And his commander, Feng Xu, who tacitly defied orders, was removed from his position in the months after the massacre.

The ABC was unable to independently verify Mr Li's account, but has viewed an Australian protection visa approval letter granted by the Australian Government after he first shared his story in the early 2000s.

The Chinese Ministry of Defence did not respond to a request for comment.

From 'ordinary student' to survivor

While soldiers were forcibly bringing the protest to an end, students were scattering in all directions amid the chaos.

Beijing Sports University student Zheng Fang was among the last group of students to leave Tiananmen Square as the tanks rolled in, at around dawn on June 4.

The 22-year-old had got about two kilometres away when he had an encounter with the military that would change his life forever.

Zheng Fang is now an advocate for human rights in China. ( Supplied: Zheng Fang )

"I was trying to save a girl near me, but I was knocked down by a tank behind me," Mr Fang said.

"Before I fell into a coma, I saw the white bones of my legs meshed with my flesh, and knew they would be gone."

The next morning he opened his eyes to find himself lying on the floor of a conference room in Beijing's Jishuitan Hospital surrounded by what he thought was "a group of angels" — but they turned out to be a group of doctors in white gowns looking at him.

Mr Fang, who later fled to the United States, woke to find his legs had been amputated.

Memories remained of troops in tanks pursuing fleeing students, while using smoke bombs to obscure their vision.

"I was just a very ordinary participant during the student movement in 1989, but during the June 4 massacre I became a special victim, survivor, and witness of it," Mr Fang said.

"I hope that tens of thousands, or even 1 million people's passion, can be awakened again."

Deaths, arrests and a cover-up

Shortly after what the Chinese Government called the "incident", it released an official death toll claiming that just 241 people had been killed — none in the square itself — with more than 7,000 injured.

The vast majority of dead and wounded, it said, were soldiers.

But estimates from non-governmental organisations put the casualties much higher.

More than 3,200 terms referencing the massacre have been censored on the internet in China. ( ABC News: Graphic/Jason Fankhauser )

Dan Wang, a prominent Tiananmen student leader who spent much of the 1990s in jail for his activism, said he thought the Red Cross Society figures of more than 2,000 dead and 10,000 injured was more accurate.

He was among more than 1,000 people reportedly imprisoned in a purge campaign to punish student leaders, intellectuals and the officials who supported them.

In what was seen as an attempt to pacify the population in the wake of the protests, China's then-leader Deng Xiaoping sped up the country's embrace of free-market capitalism.

He also launched a "patriotic education" campaign in schools and universities that emphasised the contributions of the Communist Party and the army to China's development, in an apparent effort to restore their reputation in the eyes of ordinary Chinese.

The anniversary of the massacre remains a highly sensitive topic for China's Government and has long been omitted from school curriculums.

More than 3,200 keywords related to the 1989 student movement and Tiananmen massacre have been censored on the internet in China, according to joint research by Toronto University and Hong Kong University published in April.

Mr Wang said he doesn't believe young people need to have a "deep understanding" of the massacre because it's not significantly critical to China's future.

"The incident happened 30 years ago. I think what is much more important is how young people think about China today," he said.

Dan Wang was jailed for several years in the 1990s, prompting his supporters to hold rallies calling for his release. ( Reuters: Bobby Yip )

Watch Four Corners' episode Tremble and Obey: How the Chinese Communist Party crushed democracy on Monday at 8:30pm on ABC TV and iview.

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