Australian Max Pullen had carried his country's flag for 10 years during the dawn service in Whangarei and, when he could not, he asked Ms Chestnut to replace him.
"I was overwhelmed and was ready for it as long as I did not tread on anyone else's toes but no one came forward. But I didn't see it coming," she recalled.
"I was absolutely nervous at first because having never been to a dawn ceremony here to being suddenly thrust into a role like this for a huge country like Australia is an honour."
She did five practices at the cenotaph and realised flagbearing was difficult as she had to hold the flag level with the other flags.
"I was asking everybody what to do, how long it (dawn service) takes but having a (war) veteran on my left was good because he's done it all.
"The crowd was overwhelming ... there were people everywhere. During practice, people used to gather at the cenotaph and I thought that was a lot of people, but at the dawn service the crowd was huge," she said.
Ms Chestnut cried during the service and said a woman behind her "sobbed her heart out".
She is keen to continue being the flagbearer for Australia in the future.