In the dense jungle battlefields of the south Pacific, Louis Levi Oakes was a target. Often flanked by bodyguards as he carried a large field pack with a tangle of transmission lines, the men surrounding Oakes were assigned to protect a valuable asset – his language.

A Mohawk soldier from a territory straddling the US and Canada, Oakes was the last surviving member of a secretive group of second world war soldiers who used their native language to confound and frustrate enemy forces.

On 28 May he died at his home, surrounded by family. He was 94.

Known as the Mohawk code talkers, Oakes and 16 others from the Mohawk nation of Akwesasne were part of a broader – but clandestine – facet of the allied war effort. Because critical communications were vulnerable to interception, the military recruited indigenous speakers to transmit sensitive messages. As many as 500 speakers of indigenous languages were recruited into the US military to work as code talkers, including Navajo, Tlingit, Lakota, Meskwaki, Cree and Comanche, all of whom were sworn to secrecy.

The code they used, drawn from 33 different languages, confused both the Germans and Japanese, who failed to break the code.

But the classified nature of their work kept Oakes and others silent for generations.

It was not until 2008, when the Code Talkers Recognition Act – which permitted Congress to recognise those who served in highly secretive roles nearly seven decades earlier – was passed, that the scope and extent of indigenous people’s contributions to the war effort was officially acknowledged. In 2016, Oakes was awarded the Silver Star, the US military’s third-highest combat honour, for “gallantry in action against the enemy”.

Born in 1925 in St Regis, Quebec, part of the Akwesasne nation, Oakes enlisted in the US military aged 19. Part of his decision to enlist in the US, as opposed to Canada, stemmed from a violent encounter with Canadian federal police, who arrested and beat his brother.

“When I was in Canada, the Mounties were bad. Really bad,” Oakes told the US Congress’s veterans history project. “They broke up [my brother’s] face and everything.”

The Akwesasne people, along with other Mohawk nations in the area, have a complex relationship with the US and Canada. They see themselves as an independent and sovereign nation, rather than a part of either country. As a result, the relationship between nations is often viewed as one of friendship and military alliances.

After his training at Pine Camp in New York and later in Louisiana, military leaders discovered that Oakes spoke Mohawk and assigned him to train as a code talker.

During the war, Oakes was sent to New Guinea and the Philippines and often had bodyguards to protect him from Japanese soldiers, who he said “hid up in the mountains”.

He was honourably discharged from service in 1946.

“Levi was a man who utilised his language unselfishly to preserve the freedoms bestowed upon us today,” said the Akwesasne leadership in a statement posted to Facebook.

After the war Oakes moved to Buffalo in New York, where he spent his 30-year career as an iron worker, before returning to St Regis.

“He served a unique role in fighting to protect this land, his homeland, and he’s an exemplary reminder of the many First Nations men and women who served this country with bravery and distinction,” said the Assembly of First Nations national chief, Perry Bellegarde, in a statement following news of Oakes’s death.

Last December, Oakes’s military service was honoured in Canada’s House of Commons.

“Typically when dignitaries are in the house, there’s a cautious applause,” said Marc Miller, a Liberal MP. “But when he was announced by the speaker … I’ve never heard anything like it.” Parliamentarians and guests gave Oakes a standing ovation when his name was read out. During the visit he met Justin Trudeau, and regaled the Canadian prime minister with stories of meeting his father, the former prime minister Pierre Trudeau.

Miller, a Canadian army veteran, met Oakes privately in 2017 after hearing stories of the code talkers’ wartime exploits. Oakes, seated in a wheelchair, inched forward and listened intently when Miller tried to speak to him in Mohawk.

“There’s a deep irony in the fact that the language that was used to save so many lives, and to give us the freedoms we have today, upon return, was stolen from them,” said Miller. Many indigenous peoples who fought abroad faced discrimination and racism upon their return to Canada, and a government intent on vanquishing their language and culture.

“There’s a lot of focus on truth and reconciliation right now,” said Miller, of the country’s attempts to reckon – and atone for – past injustices towards indigenous peoples. “But we really need to focus on the first word: truth. And really learn the truth about those who sacrificed so much in service to us. Levi Oakes was a hero.”