On the morning of June 28, 1914, a gunshot was fired. In that moment, the world changed forever.
The shooting took place in Sarajevo, and its victim was Archduke Franz Ferdinand of Austria. His death, and the reactions of Europe's biggest powers, would trigger the start of some of the most significant events in history.
This year marks the 100th anniversary of the start of the first world war, or Great War - a title that refers to the sheer enormity of the conflict, not a reason to celebrate.
But why should this war be any more important than any other? The answer is simple, says Dr David Smith, senior lecturer at Lingnan University's department of history: "Because it changed the world forever."
"It was the first truly modern war involving industrialised nations with the technology and mass production to kill millions of people on a massive scale.
"It was also the bloodiest war to date in human history, with up to 15 million deaths," he adds.
The first world war marked a huge difference in the people who went to war. In Britain, for example, soldiers had always come from upper class families. Suddenly, volunteers from all classes were sent to fight. It was also the first time both sides of the war "mobilised all their human and productive resources in order to win," says Smith.
History is important as it has shaped the world we see today. It also teaches us lessons so we can avoid making similar mistakes in the future. But it can be difficult to understand why you should care about a war that took place far away and long ago.
"Without the first world war, Hong Kong and China would have been very different places," Smith explains. "The May Fourth Movement, so significant for China's future history, would never have occurred without the anger of Chinese intellectuals at the Paris Peace Conference. Even more significantly, without the war there would almost definitely have been no Russian Revolution, and therefore no Soviet Union to help Mao's Chinese Communist Party take power in 1949."
It's also interesting - and tragic - to consider how young many of the soldiers were, and how they were forced to grow up unnaturally fast.
"Teenage boys as young as 16 or 17 could serve in their countries' armed forces. Teenage girls could enter the workforce to replace the men who had been called up to serve their countries.
"Younger children could suffer the sad fate of losing their fathers on the battlefield, or having them come back from the trenches crippled, blind or with deep psychological scars," Smith says.
"The centenary is important because of the lessons that need to be learned, particularly about the dangers of nationalism and the necessity of resolving disagreements between nations in a non-violent way," Smith says.
It wasn't just the inexperience of the soldiers that led to such massive losses; the men in command had too high hopes and unreasonable expectations. For example, at the Battle of the Somme, British soldiers were told to walk towards the German enemy armed with only rifles and bayonets - it had always worked in the past, so why not now? But they were no match for the Germans' machine guns, a relatively new invention. Thousands of men died that day.
In 1963, a musical called Oh, What a Lovely War! opened in London. Written by English theatre director Joan Littlewood, it is a satire on the brutality of war, the shocking number of deaths caused by the first world war, and the blasé attitude of the men in charge. Hong Kong's oldest community theatre company, Hong Kong Players, is staging the show next week, to coincide with the anniversary of the start of the war.
Jodi Gilchrist, who is directing, has long been fascinated by the war - a grandfather fought in both world wars. The show is a series of amusing vignettes, or unconnected scenes, that mock the leaders and their decisions, while news panels "that give the wrenching, hard facts and figures about the deaths, losses, and numbers in the war" are projected above the action, she says.
"The show makes fun of stereotypes, and that's where the comedy element comes out, highlighting the humour of each nationality," Gilchrist says.
Although it is satire, and therefore meant to amuse, "there are two major moods between the acts. Act 1 is more comedic, but Act 2 brings darkness, sombreness. As the reality builds for the characters, so does their disillusionment. Like the soldiers in the actual war, they didn't know what they were facing at the start. By the second act, they do."
Teri Fitsell, Hong Kong Players' chairman, believes it was important to mark the occasion in Hong Kong. "I thought we should commemorate a crucial moment in history," she says.
"It was the war that was meant to end all wars, and it was a dreadful farce where acceptable losses in a single battle were counted in hundreds of thousands. It's an iconic play - I remember seeing it several decades ago and the poignancy stayed with me since.
"Nearly all of the statistics and the vignettes are based on real events - some are exaggerated for satirical effect, but all are based in reality. What is really horrifying is that nearly all the lines spoken by Field Marshal Douglas Haig, who commanded many of the worst battles, are real, including 'The loss of, say, another 300,000 men may lead to really great results.'
"The play may be 51 years old," Fitsell says, "but it's still emotionally devastating."
The show, she says, is "powerful. It cherishes the soldiers, the ones who actually had to go over the top."
It is a fitting tribute to those many young people who lost their lives, fighting for a cause they were told was worth dying for.