Suffering from shell shock his health broke down. The family moved often as he struggled to support them on a war pension.
For his three daughters, born after his return, the war cast a long shadow.
"Dad had nightmares his whole life," Ms Nicholls said.
"You'd hear him scream in the night, but we never knew why."
She said he was a gentle man "but I remember during WWII I was complaining about there not being enough boys at the dances".
"Dad got really angry, he said, 'you've got no idea what they're going through over there'. It brought us up with a short turn, and it was one of the only times he talked about it."
Three generations of their family spent an hour and a half at the Wellington exhibition learning about their father's experience at Gallipoli - from the way the trenches were dug within earshot of the enemy to the hardships of daily life with the heat, the food and the flies.
The emotional impact struck them when they saw the giant figure of nurse Lottie Le Gallais, holding the letter marked "Killed - Return to Sender."
Ms Nicholls said her father would be grateful the story was told "because he bottled it up".
"Maybe if he hadn't, he wouldn't have been such a broken man."
More than 1.3 million visitors have visited the exhibition in the two years since it opened.
It tells the stories of seven ordinary New Zealanders and one Australian who found themselves in extraordinary circumstances during World War I. The centrepiece for each story is a figure 2.4 times human size, created by Weta Workshop.
New Zealanders make up 58 per cent of attendees with 9 per cent of visitors returning for a second visit. More than a third of visitors are aged 15 to 34.
History curator Kirstie Ross said World War I exhibitions traditionally appealed to older generations so it was gratifying that hundreds of thousands of younger people took time to visit.
"Feedback we get from younger visitors is that it has made the Gallipoli campaign and WWI more real to them. They can see glimpses of themselves, or their relatives or friends, in these figures and stories.
"We wanted to create an enduring exhibition that would commemorate the Anzacs and ensure their legacy and the memory of Gallipoli would live on."
Looking for new ways to tell the story of the Gallipoli campaign, Ms Ross says Te Papa used state-of-the-art technology, as well as some more tried and true museum techniques to bring the story to life.
"We worked closely with Weta to create an exhibition that would appeal to all ages. As well as the eight monumental figures, the exhibition also uses audio visual storytelling, 3D projection mapping, dioramas and miniatures to tell the story of the campaign. Some of the newest technology includes 3D images which were taken to help create the models of our eight figures. These different mediums make this exhibition rich and multi-faceted."
Ms Ross said the exhibition was also having an impact on older visitors.
"The older generation still bear the impact of this war with the surviving children of soldiers being particularly touched by the way the exhibition tells this story in a fresh way."
Gallipoli: The scale of our war is free and open daily from 10am till 6pm at Te Papa in Wellington.