"I've never agreed with war, it's a horrible thing and horrible to think about," he said.
"Even though this happened 100 years ago ... it will open the eyes of most people and make them think about war.
"The experience these young boys have is something that you would not want anyone to ever go through."
Smit-McPhee became involved in the series after being approached by producer Robert Connolly.
The pair had worked together on the Aussie feature film Romulus, My Father in 2007 which helped to launch Smit-McPhee's career.
The chance to team with Connolly and return home for a historical production is what lured Smit-McPhee from Hollywood where he had just made Dawn of the Planet of the Apes.
"There was nothing more important than coming back for Gallipoli," says Smit-McPhee, who was in New Zealand last year filming the Sundance-winning frontier drama Slow West.
"In a good way this is showing that soldiers aren't the patriotic brave souls they look like, it's showing them at their most vulnerable in tragic times and when they are terrified. They are human like everyone else and it definitely shows that side."
Like his character, Smit-McPhee was only 17 when he was rushing through trenches and thrusting his bayonet at the Turks on the set of Gallipoli at a rifle range in Melbourne.
"All I got out of it was tragedy and just how horrible it was," Smit-McPhee said.
Smit-McPhee's character serves in a fictitious battalion, a necessary alteration to the official campaign history, says producer John Edwards.
"We do have fictionalised elements within our story."
He says Gallipoli is not a documentary but a version of events drawn from Australian writer Les Carlyon's very detailed book.
Edwards said it was vital to portray the horrific battle scenes and the conditions the soldiers fought under.
"What's more important, the truth of the overall story or getting right exactly who trod on what piece of dirt on what day?" Edwards says.
"We have chosen to do things for the greater truth of the story whereas sometimes there will be details we have varied slightly from what happened at a particular hour on a particular day."
Edwards says the writers tried hard to strike a balance between the carnage on the battlefield at Gallipoli and the drama of the soldiers who survived.
"What you are trying to do is make the personal stories sit in harmony and shine a light on those historical events," he says.
"We've chosen - rightly or wrongly - to tell the story through the eyes of a few people and we commit to those people and we experience what they experience."
Edwards hopes the mini-series forms part of the historical recordings of the ill-fated battle in very much the same way Peter Weir's 1981 film Gallipoli, starring Mel Gibson, has been a reference tool.
TV preview
Who: Kodi Smit-McPhee
What: Gallipoli
When and where: TV3, 8.30pm tomorrow night
- AAP
