"His remains were never found. The men were blown to pieces," Mr Price said. There is a memorial for Jack at the Tyne Cot Memorial in Belgium, where his name is inscribed on the The New Zealand Apse, commemorating 1176 New Zealanders who have no known grave.
He was posthumously awarded the British War Medal and the Victory Medal in 1923.
Mr Price's father's cousin was killed on the same day as Jack.
Laury Salter Williams was also killed at Passchendaele on October 12 and was awarded the Distinguished Conduct Medal.
Mr Price, a Pyes Pa resident, has a collection of memorabilia from his great uncles, including an embroidered postcard that Mart sent to his father in March 1918 that read: "My dear Dad. I am writing you a long letter soon but this will let you see that I am still quite well and not forgotten about you. I hope that you are all well and happy and not worrying about us. Well, you will see by my address that I am at last in France. It is very interesting here, I have not been up the lines yet. I had a letter from Ned today. He is in sling camp. He is doing very well. I hope you are all doing well. Au Revoir with very best love from your loving son Mart."
Mr Price also has a hand-made leather money belt that belonged to Jack embroidered with flags of the world.
An almost 100-year-old poster with pictures of war cemeteries has Jack's death certificate affixed to it.
Mart died in 1965 and Ned in 1970. Neither man had children.
Mr Price said he did not know much about his relatives who had served and died in the war.
"All I knew was that some of the family had been involved."
He began researching his family history, which he published in a booklet for his family, and it was during this time that he discovered his family's link to World War I. "In the process of doing that, I uncovered a lot of this information. With the 100th anniversary coming up, it's all fallen into place so to speak."
Knowing his link to World War I has made Anzac day more important to Mr Price.