The People’s Republic of Amnesia: Tiananmen Revisited. By Louisa Lim. Oxford University Press; 248 pages; $24.95. Buy from Amazon.com, Amazon.co.uk

ON THE night of June 3rd-4th 1989 the Chinese army unleashed its tanks in the centre of Beijing to crush a protest that had begun seven weeks earlier against the Communist Party’s autocratic rule. Ever since, Chinese officials grow nervous in the run-up to the anniversary of the crackdown. This year they are especially jittery, fearful that the symbolic passage of a quarter of a century might encourage some dissidents to be more daring than usual in their public remembrance of the hundreds, perhaps thousands, who were killed. Security forces around the country are on heightened alert, particularly in Tiananmen Square, the plaza that has become synonymous with the unrest.

Louisa Lim, a correspondent for America’s National Public Radio, writes in her new book, “The People’s Republic of Amnesia”, that China’s modern history “pivots on that night” of bloodshed in 1989. Yet a new generation of young Chinese has since grown up that knows little of what happened, and appears not to care. Ms Lim showed students at leading Beijing universities the iconic photograph of the man standing in front of a column of tanks close to the square (above). The party’s memory-eradication campaign has been so effective that only 15 out of 100 of them correctly identified the picture. As Ms Lim notes, many young Chinese see today’s prosperity as justification for the crackdown.

This year’s anniversary will not be mentioned by party-controlled Chinese-language media. Two years ago censors even tried to block online references to the Shanghai stock exchange when it fell 64.89 points in a day, a number that sounds like June 4th 1989. Few will notice this year’s information blackout, other than the rebels of the era, some elderly intellectuals and the relatives of those who died. No one expects more than a handful of small-scale isolated efforts to mark the occasion inside China; the only exception may be Hong Kong, where controls are much lighter.

But the memories that remain are potent, as Ms Lim shows, which is why the party still expends so much effort in trying to suppress them. The author offers a series of meticulously (and often daringly) reported portraits of participants, beginning with one of the least-told stories of all: what the soldiers who took part in the killings felt about their mission. Chen Guang, now an artist in Beijing, was then a 17-year-old soldier with the martial-law troops. He describes how, in order to avoid being detected by the demonstrators, he and his fellow soldiers dressed as civilians and made their way by subway, bus or on foot to the Great Hall of the People overlooking the square. Others stormed their way into the city, shooting indiscriminately.

Inside the cavernous building “nerves were so taut that there were numerous accidental discharges, bullets flying through the ceiling of the hall”, Ms Lim writes. Mr Chen’s hands trembled so much as he gripped his gun preparing to move into the square that he was given a camera instead to record the event. He later recalls seeing hundreds of injured soldiers on the floor of the Great Hall of the People, many of them bleeding profusely after being beaten up by angry crowds.

The party, ever paranoid about the army’s loyalty, does not want people like Mr Chen to dwell on such horrors. Another, unnamed, ex-soldier tells Ms Lim that every soldier in his company had to hand in his ammunition after the square was cleared. He believed this was because the army feared the soldiers might rebel. One of Ms Lim’s most revealing portraits is of Bao Tong, an outspoken former senior official in Beijing who was imprisoned for seven years after the crackdown and still lives under constant surveillance. She says that from Mr Bao’s perspective the suppression of the protests was the “defining act” of modern-day China, accounting for its major ills today: rampant corruption, lack of trust in the government, a widespread morality crisis and the ascendancy of the security apparatus. The Chinese may not be so quick to blame the 1989 bloodshed, but most would recognise these symptoms.

Ms Lim’s book is a meticulously reported account of the events of that night and what has followed. It is particularly good at showing the extent of the pro-democracy movement—and the reaction to it. Protests erupted in more than 80 Chinese cities. Ms Lim writes at length about previously unreported unrest in Chengdu. She has painstakingly assembled detailed evidence of the beating of dozens of protesters in a hotel courtyard by Chinese police, many of them apparently to death. In Chengdu, as elsewhere outside the capital, the authorities found they were not constrained by foreign television footage when they drafted their official versions of what happened. Ms Lim says Chengdu provides “nearly the perfect case study in first re-writing history, then excising it altogether”. It is a sad reflection on the outside world’s ability to monitor a country of China’s size and secretiveness that it has taken 25 years for the record of this one provincial city to be set at least somewhat straighter.