Kereopa was also part of the NZ Coronation Contingent, that went to London for the coronation of King George V in 1911.
Maria says before she met historian Sue Baker-Wilson, her family story was forgotten.
"Maori don't talk about that time at all. "I did not know much about him before that. Sue made the connection for all of us [descendants] to get together and this is how we created the Maori Pioneers group, The Forgotten 43," she said.
Walking through the tunnels was an emotional journey to the past, she said.
"While looking at the etchings on the walls, families were crying ... I don't think you appreciate the conditions they must have been in until you are actually inside."
Maria has now collected information and photos about her great-grandfather and she is passing it on to her family.