Billy Young — known as the last survivor of the Sandakan camp — has died, aged 96, from COVID-19.

Surrounded by family in Hobart, Mr Young was crucial in remembering one of the most atrocious and neglected chapters in Australia's wartime history.

After the fall of Singapore in World War II, nearly 2,500 Commonwealth troops became prisoners of war in Borneo.

They were transported by the Japanese to Sandakan, where they were used as slave labour to build an airfield.

By the end of the war, just six of them were alive.

Joining the army at age 15, Mr Young had lied his way into the Australian Imperial Force with a forged signature from a fictitious aunt.

Speaking on ABC's Australia Wide program in 2016, he recalled lining-up to be enlisted with a friend.

"We asked: 'How old do you gotta be?' He said 19', so we said we were 19," Mr Young said.

Orphaned as a child, Mr Young had nothing to lose and was looking for adventure.

His mother had walked out when he was one and his father died in the Spanish Civil War a decade later.

Soon after his 16th birthday, the Allies crumbled under the Japanese and Young found himself as a prisoner of war at Changi.

From there, he was shipped to Borneo with hundreds of soldiers who endured harsh conditions at Sandakan: a lack of food and water, the spread of disease and prisoners being beaten, caged and tortured by the Japanese.

"People have said to me I bet you are sorry you joined the army and I said: 'No fear. It's the greatest thing I ever did'," Mr Young recalled during the interview.

After a failed escape at Sandakan, Mr Young was sent to the notorious Outram Road Gaol, where he spent six months in solitary confinement, forced to sit cross-legged for hours at a time.

Upon returning to Sydney, he wanted to reunite with his friends but could not find them.

Many had died when the Japanese forced them to march, as near skeletons, 250 kilometres through the virtually impenetrable jungle from Sandakan to Ranau.

War memory still haunted Billy

For years, his family knew nothing of his time as a teenage prisoner of war.

"We had no one who understood the trauma. There are still stories I cannot tell. I bawl like a little baby," he said.

Mr Young survived the Japanese brutality. However, he watched other POWs suffer from starvation and the worst violence.

One such victim was a young Aboriginal soldier, Jimmy Darlington, who had dared to strike a Japanese soldier for washing his clothes in the prisoners' cooking pot. He was bound and tied to sharp stakes of wood and left to suffer.

"One of the Japs grabbed a bucket of water," Mr Young says.

"Another was grabbing ropes and he put it in the water, and knelt him on the platform and tied him down with ropes, or wet ropes.

Only after Mr Young and his mates created a diversion to distract the Japanese could another Australian soldier — an ambulance officer — move in to cut the ropes. Without it, Mr Young said, Darlington would have died.

During the interview with the ABC in 2016, Mr Young's daughter, Susan, said she tried to speak to her father about his time in the war but was quickly dismissed.

"When I was about nine years old, I did ask dad a question and I just got such a strong, negative reaction from him," she said.

"I just knew so I never raised the subject again."

In his later years, Mr Young took up painting and poetry as a form of therapy and, at age 90, wrote a book with co-author and historian and friend Lynette Silver.

"He was the last surviving link and, in many ways, even if he didn't know people who died there, their relatives felt he was someone tangible who they could talk and relate to," Ms Silver said.

"Billy was a survivor because he was a larrikin. He always saw the best side of life.

"He was eternally grateful that he had survived what almost everybody else did not, so every day was a bonus for him and he lived life to the fullest."