On This Day: First World War begins after Austria-Hungary invades Serbia

JULY 28, 1914: The First World War and the ensuing slaughter of 16million people began after Austria-Hungary invaded Serbia on this day in 1914.

Russia mobilised on behalf of its Balkan ally, which had offended Vienna after an ethnic Serb shot dead Archduke Franz Ferdinand in the Bosnian city of Sarajevo.

Then Germany, which was allied with Austria-Hungary, invaded neutral Belgium on its way to France since it could expect the French to attack on behalf of Russia.

The Germans, who had been spoiling for a war to increase their power amid growing imperial rivalry, hoped to defeat France quickly before Russia could gather troops from across its vast territory and attack her.

Britain, which was allied with both France and Russia in its Triple Entente or Alliance and had been enraged by the ‘Rape of Belgium’ that left 6,000 civilians dead and hundreds of villages razed, then declared war on Germany on August 4.

A standing army of 733,000 men was called into action in August 1914, followed by a massive recruitment drive and later conscription.

The Germans, who had gambled on the UK staying neutral, got within 43 miles of Paris before the British, whose troops are shown marching through ruins in British Pathé footage, helped turn them back.

They struck the German flank at the Marne, forcing Kaiser Wilhelm II, a cousin of both the British and Russian monarchs, to order a retreat to protect their rear.

This triggered the great Race to the Sea that established a Western Front that stretched 400 miles from the Belgian coast to Switzerland and barely moved in four years.

Trench warfare set in and a costly war of attrition on this single front led to 13.5million casualties on both sides.

By the end of the conflict, four years later, more than 8.6million men from across the British Empire had been mobilised – and almost a million of them were dead.

[On This Day: The Battle of Verdun – the longest engagement in WWI - ends]

The scale of the war, which was fought between 60million Europeans and 10million men from elsewhere, and the slaughter, had hitherto been unimaginable.

In Britain, the catastrophic waste of young life was best symbolised by the Somme, where 19,240 Britons were killed in the bloodiest day of battle of the entire war.

To Canadians, Vimy Ridge, where 3,598 died in a three-day period in one of the most heroic and successful Allied engagements of the conflict, remains hallowed ground.

Australians and New Zealanders deeply remember Gallipoli, where 11,430 of them died in a failed invasion of Turkey, which entered the war in November 1914.

And the French were most haunted by Verdun, whose defence cost them 156,000 lives, 386,000 casualties and sucked in three quarters of their 8.6million soldiers.

On the Allied side, the war also sucked in Japan in 1914, Italy, which ditched an earlier alliance with Germany and Austria Hungary, in 1915 and Romania in 1917.

The biggest turning point in the stalemate came in 1917 when Russia made peace with Germany after the Bolshevik Revolution and America joined the Allies.

[On This Day: The tank makes its debut in World War I]

On the one hand, Germany, which lost 2.5million men, could now concentrate on a single front and so had the confidence to launch an even bigger attack in the west.

But on the other, the U.S. had an unrivalled industrial production and capacity to mobilise troops – and ultimately changed the balance.

Germany, who realised the war was unwinnable after their last major offensive in the July 1918, signed an Armistice to end the fighting on November 11 of that year.

The conflict changed the face of the world, wiping out both the Austro-Hungarian and Ottoman empires and, in spite of short-term territorial gains, began the process of withering the British one.

America also became the pre-eminent power while the new Soviet Union threatened to spread its communism, which contributed to another rise in nationalism elsewhere.

In the aftermath, Erich Ludendorff and other German generals, also helped perpetuate a dangerous myth that since the country had not been defeated militarily – with no official surrender – she had been stabbed in the back by her civilians.

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Jews, as prominent members of a new republican government, were particularly blamed for cheating Germany of victory and accepting the ‘shameful’ peace.

Adolf Hitler, having also been influenced by Ludendorff’s theory of Total War, used this anger to help his Nazi party rise to power and trigger an even deadlier conflict.