Sergeant Jack Tredrea wondered just what he was getting into when, as he prepared to infiltrate Borneo, he was offered a cyanide pill.

It was in event of capture by Japanese forces and the certainty of torture and execution.

The former member of Z Special Unit, the top-secret commando organization recruited during World War II to fight behind enemy lines, said he signed up “maybe because of the word ‘special'”.

“We didn’t know what it was and what we were in for. But we were young and wanted to get into it so we volunteered,” he told AAP.