"His service record fits the man in these images like a glove. He was transferred from the Pioneer Battalion to serve with the New Zealand Division headquarter staff behind the lines of the Somme in April, May and June 1916.
"He was transferred back to the same Pioneer battalion when the New Zealand Division entered the battle [from 15 September]."
The woman in the photos, who is shown wearing the officer's uniform and also sitting playfully on his knee, has not been identified. She wears a wedding ring.
Records show Captain Chapman, who emigrated to the United States via Canada in 1924, was not married, leading to speculation about the nature of his relationship with her.
Officer in mysterious photo identified
Mystery man?
Captain Albert Arthur Chapman:
* Born in Tasmania in March 1880.
* Lived in Dunedin, where he worked as a shipping clerk.
* Probably served at Gallipoli.
One of 15,000 Kiwis to fight in the Battle of the Somme.