The Treaty of Waitangi was first signed in the Bay of Islands on February 6, 1840
Over the following months, a further eight Treaty sheets were signed in various places around the country, including in Tauranga, she said.
One of the sheets arrived in Tauranga after many years of violence and bloodshed had decimated the local population.
McCauley, who is a historian and Tauranga City librarian, said not all the chiefs of Tauranga Moana signed the Treaty sheet, which in the end had 21 local signatories.
Ngai Te Rangi chief Hori Tupaea and some other Otumoetai Pa leaders refused saying they saw no clear purpose for doing so, she said.
McCauley's book profiles several of the signatories to the Treaty and one of the witnesses but no information could be found about half a dozen others, she said.
She said one of the prime sources for the book's content was the journals of missionary Reverend Alfred Nesbit Brown who bought 12 hectares of land in Otumoetai.
Brown was sent two Treaty sheets at the Te Papa Mission Station in Tauranga and was asked to gather signatures from leading chiefs which proved difficult after one of the chiefs was murdered the day before the documents arrived.
Words from Brown's journal also features on the book's front cover, McCauley said.
This book puts into context the Treaty of Waitangi and Tauranga's importance in the signing of the Treaty, she said.
"I think it's a really important story. All the kids are taught about the Treaty in schools but not a lot is known about Tauranga's specific role in the signing of the historic document.
"This book sheds more light on the significant role Tauranga Moana played in the country's history in terms of the Treaty of Waitangi."
McCauley said writing the book had taken three years.
"Every book is like having a baby, but this one was like an incredibly long labour and now the baby is ready to go out into the world. I hope people like it."
The book is illustrated by Whare Joseph Thompson, and designed by McCauley's third cousin Sarah Elworthy.
One of McCauley's previous titles Motiti Blue and the Oil Spill: A Story from the Rena Disaster won the best non-fiction category in 2015 New Zealand Book Awards for Children and Young Adults.
Another title Taratoa and the Code Conduct: A Story of the Battle of Gate Pa, was a finalist in the 2015 LIANZA Children and Young Adult Book Awards.
Treaty of Waitangi: Tauranga
On March 30, 1839, a deed of sale was signed for the purchase of a Te Papa block of land to missionary Reverend Alfred Nesbit Brown.
Treaty first signed in the Bay of Islands at Waitangi on February 6, 1840.
Over following months a further eight Treaty sheets were signed in various locations around Aotearoa, including in Tauranga, believed to be between April and May 1840.
