Walter Chissell, of Whangarei, returned from the war with a leather satchel containing photographs, books and letters which belonged to a German soldier called Eddi Fickeis.
Little is known of how Sgt Chissell came into possession of the satchel, but his family and descendants said he spent decades trying to find the original owner.
Sgt Chissel's daughter, Shirley Witehira, said she had known about the satchel since she was a little girl.
``I don't really know how got it. He acquired it, I think, in Italy.''
The family enlisted a German translator to look at the letters in the satchel. However, they were written in a different dialect to what was understood today.
``It was old German and [the translator] couldn't do it properly.''
The satchel was left in the possession of Ms Witehira's sister-in-law Elainee Witehira, in the hope her European ancestry might be useful in the search for the family.
Despite searching ``all his life'', Sgt Chissell died in 1991 without solving the mystery.
``We carried on the legacy. And if I died, my daughter was going to do it. It was important to find the family,'' Elainee, who lives in Dunedin, said.
The satchel was special to Sgt Chissell.
``He used to sit and hold it ... He would look at the pictures in it and the pictures of the children and wonder where they were.''
Recently, Elainee's daughter Xzenia suggested posting on Facebook.
Someone ``accidentally'' saw the post before travelling to Germany and took the information overseas.
One thing led to another and eventually the family was found.
``There were so many unexplained things that happened,'' Elainee said.
In fact, the story seemed so unlikely the family in Germany initially thought it was a scam.
Only when they saw the photos from the satchel did they believe the story was true.
``They are over the moon. They can't believe it,'' Elainee said.
It was an emotional story of caring, love, determination and ``never ever giving up'', as well as bringing together people from ``all walks of life''.
Mr Fickeis' son Axel and his family will travel to New Zealand in February to be presented with the long-lost satchel and personal items.
Sgt Chissell's family initially believed Mr Fickeis died in the war, but theynow know he survived.
Dunedin film-maker Wiebke Finkler, who helped in the search, wants to produce a documentary on the story.
``Even she was blown away by what happened,'' Elainee said.
They were attempting to raise funds to make the film.
