"Being able to play mine at the Palais, the greatest cinema in the world is pretty exciting to me.
"I always knew the story was really powerful.
"I was a journalist in Wellington at the time Brigadier Mortlock announced the plan and everyone thought he was insane, including me.
"I was proved wrong, what they did create was a lasting peace."
In place of guns the peacekeepers had guitars and in place of fighting they shared the haka with the Bougainvilleans, he said.
"This documentary shows how effectively a peaceful resolution can be achieved by using a culturally inclusive approach," he said.
"Instead of rifles they brought haka and guitars, culture instead of conflict and it worked.
"Whereas most peacekeeping operations traditionally fail, this one has been an enduring success."
The civil war was the largest conflict in Oceania since World War II with an estimated 20,000 casualties.
The documentary focused on how Brigadier Mortlock's mission succeeded despite scepticism following numerous failed attempts from different countries both through military action and peace talks.
Brigadier (retd) Mortlock, who lives in Napier and Wellington, said he was absolutely delighted but not surprised by the accolade because Watson was able to tell the story so well.
"Those who take part in New Zealand's military operations tend to be the harshest of critics when watching documentaries about their efforts.
"In this case, Will Watson's film, Haka and Guitars, is very well done and deserves its prize-winning applause.
"Will has captured the enormously brave efforts of the Bougainvilleans to bring the civil war to an end."
At the time it was a very improbable story but Watson was thorough and portrayed it realistically, he said.
"It was a lot of fun to make."
The NGO will utilise the film within their programme globally to aide in their mission's outreach to promote peace through the usage of media, film, and arts.
New Generation in Action's goal is to bring culture to communities in which they work while simultaneously assisting with peace efforts.
The film fulfilled the organisation's United Nations group mission of assisting in world peace, preservation of indigenous cultures, women's empowerment and assisting in economic sustainability through media, film, and the arts.
Havelock North-born Watson is a best-selling published, journalist, photographer and has worked with BBC, ITV, Al Jazeera and Mori Television Service.
Haka and Guitars is William's first feature documentary and has already won numerous international awards.
He is currently working on funding to complete a documentary called "A Cultural Soldier".
Watson is also slated to receive an honour for his contribution in Humanitarian, Media and Arts from AFI World Peace Initiative's founder, multi-media talent Angelique Mont.
