It may have been not much more than a sandbank, but it did boast some fine examples of European architecture, used as offices by foreign companies and consulates, a few walled comprador villas, tree-lined streets, the shady French Gardens, a Catholic chapel and a Protestant church, and two pedestrian bridges leading into and out of the teeming city beyond.

An ongoing wave of strikes across Guangzhou, occasionally turning violent, meant that foreign troops were stationed at the bridges behind barbed-wire barricades to prevent any incursions into the concessions.

Merlin, a Parisian in his mid-60s, was not a popular governor-general in Indochina. After administering France’s colonies in West Africa and Guadeloupe, he had become a hardliner, refusing any accommodation with local people regarding their own governance.

The event proceeded smoothly enough despite the British-owned Victoria being renowned for having become shabby and for serving atrocious food.

About 50 guests attended, with the officers of the French gunboat Craonne joining local French businessmen, their wives and the foreign press in the city. All were seated at one long dining table, the floor-to-ceiling windows in the hotel’s ground-floor ballroom left open in the hope of cooling breezes.

The governor-general was kind enough to answer questions from assembled reporters, and mingled and gossiped with the leading lights of the French community, before giving a short speech extolling the supposed tranquillity and growing prosperity of Indochina under French rule.

The week before, Merlin had appealed to the Japanese authorities to clamp down on exiled Vietnamese activists based in Tokyo, and other cells of resistance to French rule had been established in Siam (modern-day Thailand), Shanghai and Seoul.

The colonial authorities in Hanoi were nervous, as the Sûreté secret police in Hanoi and Saigon had been picking up rumours of more concerted action to come. Fearing a possible assassination attempt, Merlin had travelled alone to Guangzhou, leaving his wife, Marie-Madeleine, and son André (a keen young tennis player who would later represent France in the Davis Cup) in Hong Kong.

But Bertram Giles, the British consul-general in Guangzhou, had not been informed either of Merlin’s arrival in his concession, or the banquet at the Victoria, and so had provided no additional security.

And while the Guangzhou Police Department had stationed men on the Chinese side of the bridges to stop any protesters trying to cross onto the island, no personnel were posted on Shamian itself.

Consul de Casabianca proposed a toast to Paris’ Far Eastern Empire, champagne glasses were raised and dinner was served – the assorted French citizens likely nervous given the Victoria’s poor gastronomic reputation.

At 8.30pm, waiters in white livery entered the ballroom with large tureens of soup. An Asian man in a white linen suit was briefly seen peering through one of the open windows, and then a leather bag sailed through the same window, landing on the dining table. The bag contained a bomb, and it exploded on impact.

The scene was carnage. Andre Demaretz, of New York’s General Silk Importing Corporation, and his wife, only recently arrived in China, were killed instantly. Paul Rougeau, soon to retire from the Banque de l’Indochine and return to France, was blown across the room and died.

Gaston Pelletier of the French Indochina Hospital was found dead under the dining table. One poor woman’s carotid artery was severed by glass from a shattered mirror. She bled to death on the ballroom floor. The representative of a French textiles firm was brutally stabbed by silver cutlery blown off the dining table by the blast, and died of his injuries.

Five other French guests and three Chinese waiters were seriously wounded, including de Casabianca. His life hung in the balance for several days following the attack. He eventually recovered, though part of his left arm had to be amputated.

Merlin miraculously survived, shaken but otherwise unscathed. As the bomb landed, Merlin’s quick-thinking aide-de-camp, Captain Berrier, pushed the governor-general under the dining table, where he avoided the worst of the blast. Berrier was hit by shrapnel and badly wounded.

The assassin had miscalculated, assuming that the governor-general would be seated at the head of the table when in fact he was in the middle, and so avoided the worst of the fallout. Seated at the head of the table had been an unfortunate silk merchant, Henri Gerin, who did not survive.

A number of the reception’s guests, two Parsee men who happened to be passing and witnessed the attack, as well as a cook from the hotel, chased after the man in the white suit who had thrown the bomb. They were joined by a group of American sailors temporarily stationed on Shamian.

Running through the French Gardens, a small park, the man took out a revolver, turned and fired at his pursuers. He missed and ran towards the French Bund, the water’s edge.

Across just 10 metres or so of the Pearl River was the city of Guangzhou, where a man could easily disappear into the dark laneways and rookeries, never to be seen again. But how to get across?

Sikh policemen, employed by the French police on Shamian, began searching the bushes that lined the Bund. The waterway was clear, no passing boats, no sampan taxis to board. The man took his chance as the Sikh constables closed in, and dived into the water.

Perhaps he couldn’t swim, maybe the current was too strong. Either way, the next morning his bloated body washed up further down river. Police found a gun cartridge matching those fired in the French Gardens in the dead man’s jacket, along with a pocket watch stopped at 8.47pm precisely, the moment he had leapt into the water.

The body was identified as an “Annamite”, as Vietnamese were then called, and the Hanoi Sûreté’s fears of violent anti-colonial struggle appeared to be confirmed.

It might have been the case that such an awful attack on the ballroom of the Victoria Hotel, the dead and injured, the plot to kill France’s main man in the Far East, would lead to outrage and opprobrium. And so the assassination duly did in the tabloids of Paris, London and Hong Kong. But less so in Indochina.

The local papers in Saigon played up the scene of Merlin cowering under the dinner table, and then the French community, both in southern China and Indochina, turned against the governor-general.

On the evening of the attack, Merlin left the hotel and returned to the waiting Craonne, remaining on board the gunboat. He cancelled a planned high-profile lunch the next day with Sun Yat-sen, the founder of the Republic of China, and immediately sailed back to Hong Kong at full steam.

The local community was angered that Merlin did not stay long enough to visit those in hospital or see the French dead buried.

Back in Hong Kong, the British were taking no chances. Armed police launches escorted Merlin’s boat to dock while soldiers of the East Surrey Regiment were stationed on the pier.

A police escort with motorcycle outriders took Merlin to secure lodgings, where his wife and son were already under armed guard. A few days later the governor-general embarked for Saigon.

Despite the identification of the drowned attacker as an Annamite, the French resisted the notion that the assassin was from Indochina, or that he might be of some education, although the evidence was hard to refute. The corpse was well dressed, the hair cut en brosse and the fingernails manicured.

A local tailor who had made the suit was questioned, but knew little. A revolver found in the river and some Hong Kong dollars in his pockets indicated – so said the French – that the bomber was a professional assassin sent from the British colony.

Both the British and French protested that, whether Chinese or Annamite, Guangzhou could be a home to revolutionaries or assassins.

Draconian regulations were introduced to police all Chinese working on Shamian Island, which led to a strike by cooks, houseboys, the Chinese employed in the European police forces and, of course, the staff at the Victoria.

An anonymous letter, accompanied by a photograph, was delivered to the Guangzhou newspaper Xianxiang Bao two days after the bombing.

It identified the bomber as Pham Hong Thai and included his testimony admitting to the attack, declaring Thai as a member of the Vietnamese Revolutionary Army and that a 10-man team had been dispatched to Guangzhou to kill the governor-general.

Thai had posed as a journalist to gain access to Shamian, while it was thought that other members of the cell may have also been on the island posing as waiters, cooks or rickshaw pullers.

The missive concluded, “I will not be regretful for this deed even if I die. I wish that what I have done will make other nations understand the suffering of my people and help us.”

Thai was just 28, from Hanoi by way of Nghe An province. Never settling to a trade, he had moved to Laos in 1918, then on to Thailand, where he had married and had a son, and then eventually settled in southern China.

In Guangzhou it appears he joined the Tam Tam Xa, or the Society of Like Hearts, a group of young activists opposed to their more conservative elders in the liberation movement. Their aim was to awaken the people of Indochina to the anti-colonial struggle.

The French tried to paint Thai as a terrorist, a mad anarchist bent on murder and destruction, but the group had chosen to target Merlin specifically because he was recalcitrant on Indochina and had launched a campaign, as historian Tim Harper writes in his 2020 book Underground Asia, “to silence and eliminate patriots outside Vietnam”. Merlin retired soon after the attack, in April 1925, and died a decade later in Paris.

Naturally, the Tam Tam Xa claimed Thai as a martyr. His photograph and the story of his life and death (sometimes suggested as a self-sacrificial act to prevent capture) circulated widely, throughout Guangzhou, southern China, Hong Kong and, of course, Indochina.

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The French consulate in Guangzhou was annoyed that the Nationalist government arranged for Thai’s body to be disinterred from a pauper’s grave and reinterred in the city’s Huanghuagang Cemetery, next to Chinese revolutionaries who had died in the uprisings of 1911 that saw the creation of the Chinese Republic.

But by then the French authorities in Hanoi had lost control of the narrative. Pham Hong Thai was, and is still, a national hero.

At the end of 1924, a man calling himself Nguyen Ai Quoc (“Nguyen the Patriot”) arrived in Guangzhou and appealed to the surviving members of Tam Tam Xa to join his new Vietnamese Revolutionary Youth League.