The organisers of the Fields of Remembrance exhibition at Auckland Domain have encouraged relatives to take home the crosses bearing the name of family members in the final days of the month-long event.
But Aucklander Tim Carter, whose great uncle died in the war, said he discovered someone had beaten him to it.
"A friend rang and told me that the cross was gone. He knew where it was because we found it earlier in the week.
"It was very disappointing because I had been looking forward to picking it up and taking it home. But it had already disappeared."
Carter said his friend saw a member of the public picking up handfuls of the crosses, apparently at random. The woman had "a dozen or so" crosses under her arm.
"She said she wanted to have an arrangement in her garden," Carter said.
"I don't think it was a malicious act. I think it was just in ignorance that she didn't realise the significance of these crosses to other people.
"I've got over it now but I was quite angry yesterday to think that I was the only person in New Zealand who was connected to that cross. He hadn't any descendants apart from myself that were still alive."
Carter's great uncle, Private Henry Carter, died on October 12, 1917 in the Battle of Passchendaele - a battle known as New Zealand's "blackest day" because of the huge loss of life.
Fields of Remembrance Trust vice chairman Graham Gibson confirmed security guards had caught a couple of tourists wanting to take crosses as souvenirs when the exhibition first opened a month ago. They were very apologetic when the significance of the crosses was explained to them.
But the trust had not seen a member of the public taking large numbers of crosses at random yesterday.
"I don't know about that. We were monitoring from a distance all yesterday so if anything unusual was happening or someone was trying to walk off with 10 or 12 crosses we do approach them and ask 'What's your interest here?'"
The claiming of crosses was done on an honesty basis, he said.
"We've got no control over who is claiming relatives' crosses. How do we do it? Do we line people up and demand identification? You can imagine it from our side of the fence."
Two people had sought permission from the trust to take multiple crosses for family members outside of Auckland. There were also instances where more than one family member had wanted to claim a single cross. The trust decided to stay out of these cases, Gibson said.
"I didn't want to get involved or to become the judge or advocate and decide who got it. That wasn't our place to do that."
The exhibition was an "enormous success", he said, and he hoped it would not be undermined by the claiming process. He said he would arrange to provide a new cross to Carter with his great uncle's name on it.
"We've had thousands of people come through. It's been mind-boggling. We had a person from Invercargill who saw coverage of the exhibition and they got on a place the next day to claim their relative's cross."
In all, there were 18,277 crosses representing every New Zealander who died in WW1. It was part of the 100th anniversary of Armistice Day, when hostilities ceased across the many battlefields of the 'Great War'.
Relatives were able to claim their crosses yesterday, today, and tomorrow. The exhibition ends on Tuesday and leftover crosses will be gifted to the Returned and Services Association, schools, or "disposed of respectfully".
