History has not been kind to the teenager who triggered the First World War by assassinating Archduke Franz Ferdinand on a sunny Sunday morning in Sarajevo.

So colossal was the impact of his actions and so modest his backwoodsman background that the story of Gavrilo Princip has often been overlooked, misrepresented and misunderstood.

Muddled theories, often as batty as they are unverifiable, have circulated ever since Princip fired his Browning 9mm pistol on June 28, 1914: he was working for the Freemasons, an agent of the Russian secret service, a diehard Serbian nationalist, an unwitting puppet of German warmongers.

Even the most famous photograph of Princip, showing him ‘‘under arrest’’ after the assassination, is problematic. It has been used by historians, newspapers and broadcasters, from AJP Taylor to Wikipedia, and they are all wrong. The man was an innocent bystander called Ferdinand Behr.

So, stripped of the prejudices and mistakes of those who came later, who is the real Gavrilo Princip? He was born a citizen of the Austro-Hungarian Empire in summer 1894 in a small village called Obljaj. The date is disputed, recorded as June 13 and July 13 in local records, most likely using the old Julian calendar which was then 12 days behind the modern Gregorian calendar. No matter which date is accepted (June 13, June 25, July 13 or July 25), Princip was 19 when he shot the Archduke.

His home village is in what is now Bosnia though when he was born, no such nation existed. Instead, the west Balkans was a mosaic of land parcels mostly divided between foreign empires.

For four centuries his home was occupied by the Ottomans, which led to many local Slavs converting to Islam, progenitors of today’s Bosnian Muslim population. But in 1878, Bosnia was ‘‘flipped’’, occu- pied by Austria-Hungary, and any sense of Bosnian national identity was then a flight of fancy.

The Slav community that Princip’s family belonged to followed eastern Orthodox Christianity, making him an ethnic Serb – although this did not make him Serbian. To be Serbian you had to live in Serbia, land east of Bosnia which had bloodily and recently won independence from Ottoman control.

The Princip family were at the bottom of the pecking order. They survived like medieval serfs, obliged to give almost all their meagre farming earnings to overlords. They lived in a hovel with a beaten earth floor and rock walls roofed by shingles cut from local timber. Six of Princip’s eight siblings died as infants.

To seek a better life, he left Obljaj in 1907, enrolling in a secondary school in Sarajevo, capital of the Austro-Hungarian colonial province. There he shone, outdoing classmates from richer backgrounds. But it was in Bosnia’s schools that the green shoots of nationalism were showing and he soon fell in with youngsters demanding freedom from colonial rule.

A key mistake is made by historians who say that Princip supported Serbian nationalism, the theory that the Balkans should be ruled by an enlarged Serbian state. This is not true. All the evidence shows that Princip supported Slav nationalism: the idea that foreigners should be driven out so local people could rule, no matter if they were Serbian, Croatian or from other ethnicities.

After leaving school in Sarajevo, Princip travelled to Serbia where he hatched the assassination plot. There he received help from Serbian nationalists, but Princip’s motives were never exclusively Serbian.

Arrested moments after the shooting in Sarajevo, he was under the 20-year age limit required by Habsburg law for the death sentence. Instead, he was sentenced to 20 years in jail, to be denied food once a day each month. He died in 1918, shortly before the end of the war. Aged 23, his body had become racked by skeletal tuberculosis that ate away his bones so badly that his right arm had had to be amputated.

*Tim Butcher’s book on Princip, The Trigger, will be published in May 2014

Also in Inside the First World War, part one:

World War 1 and the Europe we left behind >>

Who was to blame for the First World War? >>

Mother, tell them I'm only 17: Soldier's last letters home >>

The Suffolk lad who came out fighting >>

Art of war: The Kensingtons at Laventie >>

Your First World War memories >>

Military balance and a new age in modern warfare >>

From Lieutenant Macmillan to ‘Supermac’ – a Prime Minister's war >>