"What he achieved in his life was amazing."
Mr Chambers has read that to defend an out-post, his grandfather commanded 100 soldiers against 400 Turkish soldiers for 30 hours, and then wrote letters to the families of those killed.
Mr Chambers said he was happy to loan a diary and other possessions to the MTG.
"They'd been locked up in a safe for 100 years," Mr Chambers said, "it's fabulous that people can appreciate and see them.
"In terms of money [the diaries] are worth nothing, but historically you can't put a value on them."
In the exhibition Major Chamber's items are among those of others who fought, like Captain Earnest Harston, Sir Andrew Russell, Sergeant Edwin Cornford and Leo Bestall, the first director of MTG Hawke's Bay.
Their guns, bugles, and poems are displayed underneath photos, maps, and visual guides which let visitors walk in the footsteps of the region's soldiers - from the excitement of enlistment, to training, reaching "the nightmare of the Western Front, The Somme and Passchendale", before armistice.
Curator of Social History Gail Pope said most museums had done an exhibition for the centenary, but "we needed to tell our story, the Hawke's Bay story."
While it was hard to separate the region's story from the nations, "there is a Hawke's Bay voice".
"[Soldiers] have this yearning for home in their letters. Because the letters were censored they were always asking about what was happening at home. It's very personalised and telling."
As well as military memorabilia there are also nurse's uniforms, telegrams, and "souvenirs" from Egypt.
"Soldiers collected artefacts, it's what they did on their days off. They were tourists for awhile before they were sent to Gallipoli."
Those on the home front are not forgotten, with a section devoted to the men, women, and children in Hawke's Bay.
"We tried to cover all aspects of the war. But it's such a huge story to tell."
It was important children understood the war, so the interactive exhibition invites children to try on military attire, climb into a replica bunker, and measure themselves "to see if they are fit for war". In the weeks before Anzac day, visitors have also been invited to pin a hand-made poppy near the exhibition, often with hand-written messages of remembrance.
- The MTG will be open on Monday, April 25, with free admission and a coffee cart on site.