Burn returned to New Zealand just after the outbreak of the war.
In May 1915, the tall grey-eyed single man, who was then New Zealand's "only qualified aviator belonging to the Defence Forces of the Dominion", joined a Royal Flying Corps unit in the Mesopotamian (Iraq) campaign against the Ottoman Empire.
Based at Basra, they were equipped with a motley collection of second-rate aeroplanes.
"They were marginal aircraft at very best, operating in a very hot and sand-blown environment where engine failure was the biggest risk to them," said Errol Martyn, author of A Passion For Flight: New Zealand Aviation Before the Great War.
Flight Lieutenant Burn flew reconnaissance flights over the Turks' positions, coming back with invaluable intelligence on their deployments and numbers.
On July 30, 1915, the two-seater unarmed Caudron biplane being flown by Australian Lieutenant George P. Merz, with Flight Lieutenant Burn as observer, suffered engine trouble and was forced to land in the desert about 32km southeast of Nasiriyah. They were immediately attacked by a number of well-armed Marsh Arabs of the Beni Malik tribe, according to military documents.
A subsequent Court of Inquiry heard that the two airmen, armed only with revolvers, fought a running battle for about 8km, killing one and wounding several others.
"There's no real firm evidence to confirm exactly what happened. Their aeroplane was found and the fabric slashed to ribbons and their bodies were never found at all," Martyn said.
According to one eyewitness report, when one of the airmen was wounded his comrade stayed beside him.
Flight Lieutenant Burn, remembered at the Basra Memorial in Iraq, was the first New Zealand airman to be killed on active service, and Lieutenant Metz the first Australian.
They are also commemorated by the Burn-Merz Shield, given to the winners of a rugby match played every year since 2004 between the Royal New Zealand Air Force and Royal Australian Air Force.
About 750 New Zealanders served in the air war from 1914-18 in the air and on the ground in Britain, the Western Front, Gallipoli, Palestine, Mesopotamia, the North Sea and the English Channel. A total of 79 died, of whom 63 were killed flying.
In 1922, Flight Lieutenant Burn's mother, Isabella Mathilda Burn, of Hereford St, Christchurch, was given his war pension, which totalled 54 pounds and 15 shillings.
His death was the first of several tragedies for the family.
Seven days after he died, his 27-year old brother, Trooper Robert B. Burn of the Canterbury Mounted Rifles, was killed at Gallipoli during the night advance of August 6. Another brother, John, remained a civilian but died aged 30 in January 1919, a victim of the Spanish Flu.
And foster brother Jack, a 15-year-old pupil at St Andrew's College in Christchurch, was lost off the ferry Maori only a few days later.
"It was not just one tragedy, but tragedy upon tragedy," Martyn said. "You have to wonder how the mother coped."
Read earlier stories in this series here.