During his service time with the 3rd Field Ambulance Australian Army Medical Corps at Gallipoli in 1915 he was known as Private John Simpson and his bravery was never in doubt.
He forged a reputation as a man not afraid to put his life on the line to help his wounded cobbers.
He used one of the donkeys which had been taken ashore at Gallipoli for carrying water as his four-legged "ambulance" and carried wounded troops day and night from the frontline fighting back down to the safety of Anzac Cove.
One observer noted that he defied "deadly sniping down the valley and the most furious shrapnel fire".
His bravery was never in doubt but his mortality was.
On May 19, 1915, while carrying two wounded soldiers he was gunned down by machine-gun fire and died.
He was later buried on the beach at Hell Spit.
His deeds created huge acclaim and were immortalised in the painting, which is also known as The Man with the Donkey.
The painting itself was also used as the basis for sculptures and memorials.
While the painting is a memorial to the service and devotion of Private Simpson, the original photograph used to create it was not actually of Simpson but of a New Zealand stretcher bearer by the name of Dick Henderson who took over the donkey-utilising role.
This is where the remarkable, and previously unknown, link between the two men from the same small Hawke's Bay township, kicks in - a link they had been unaware of.
The painting was the work of Sapper Horace Millichamp Moore-Jones who had taken part in the New Zealand Expeditionary Force's landing at Anzac Cove.
He was a recognised artist at the time.
"Sapper Moore-Jones was my great uncle," Mr Jackman said.
What inspired the painting was the photograph taken by Sergeant James G Jackson.
"And he was my great uncle," Havelock North jeweller Bruce Jackson said.
"A strange and unique coincidence," was how Mr Jackman put it.
He is the president of the Havelock North Business Association, has been living in the village for nine years and Mr Jackson, who runs the Unio goldsmith shop, has been there for 11 years.
"Through business we've known each other for quite a while but never had any idea of the link we had through this," Mr Jackman said.
Discovering it came about through the power of social media.
Mr Jackson posted a piece on Facebook about news that a painting of Simpson and his donkey was up for sale - and that it was the photograph taken by his great uncle which had sparked its creation.
That posting was spotted by Mr Jackman whose family, through the generations, had long been aware that the painting was by Sapper Moore-Jones - from within their family.
"His (Bruce's) great uncle had taken the photo and my great uncle painted it - I couldn't believe it," Mr Jackman said.
He immediately posted that news on Facebook and Mr Jackson was delighted to learn of the link.
He was pretty low key about it though, saying "nothing surprises me too much these days but it is remarkable".
Of the sale which he had noted, Mr Jackman said the family had long known there were seven paintings of Simpson, but there was only one by his great uncle and that had been gifted by the family to the Auckland War Museum.
"When he came back from the war he lived in Hamilton where he set up an art school - and the story which has long been in our family was that six of his students painted the others," Mr Jackman said.
That, he added, was why he would not be interested in buying any of the six when they occasionally went up for sale.
"Because he wouldn't have painted it - the one he painted is in the war museum."
Both Sapper Moore-Jones and Sergeant James Jackson got through the war and eventually met up in Dunedin, where Mr Jackson agreed to loan Mr Moore-Jones his photo for him to paint the picture.
Whether they had met up during their time on Gallipoli was unknown, Mr Jackman said.
"We'll never know."
He said neither had ever lived in Havelock North yet their two great nephews now did, and had known each other for some time without ever knowing the unique Anzac link between them.
Mr Jackson said he would make up a special Anzac Day display for his shop window showing the painting and the photograph.
"It's quite special."
