Those harsh experiences also left an indelible mark on the families they returned to or left behind, still felt 75 years after the end of the war.

Greg Coombs' father, Joe Coombs, saw the mushroom cloud from the atomic bomb dropped on Nagasaki on August 9, 1945. He was imprisoned in Nakama, working in the coal mines when the war ended.

Joe Coombs had enlisted just shy of his 21st birthday in 1941 and was sent to Singapore, arriving a few weeks before the city fell on February 15, 1942.

He would spend the rest of the war as a prisoner of the Japanese, narrowly avoiding being sent to work on the Burma Railway, where more than 100,000 Allied prisoners died.

He ended up in Japan, working for three years in shipyards before being sent to work in coal mines for the final six months of the war.

Mr Donaldson said his father, who died at nearly 98, had survived through sheer luck.

"Dad was a very gentle man, you know. Quite a character. He didn't hold grudges," Mr Donaldson said.

In 2009, Joe Coombs, then 88, returned to Japan in an effort to get an apology from Taro Aso, the then Japanese prime minister whose family had owned the mines in the war. He didn't receive an apology.

"You'll never forget the bad times. The memory will always be there," Joe Coombs told the ABC at the time. "With an apology the pain will go."

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Andrew Donaldson's father, Bert Donaldson, had survived the battalion's Malayan campaign but was imprisoned for the rest of the war after Singapore fell. He was in the same battalion as Joe Coombs.

Mr Donaldson said mateship had been critical to the survival of his father and the other soldiers who were imprisoned.

"To be honest, I didn't respect him as much as I should have, looking back. Because I now respect him as an absolutely outstanding individual and what they survived, I don't think I could possibly do," Mr Donaldson said.

Anne Buttsworth never met her father, who died as a prisoner of war in Japan. Hal Buttsworth, who made his come in Canberra after marrying, sailed for Malaya in January 1941; Ms Buttsworth was born in April 1941.

Also a member of the 2/19th Battalion, Hal Buttsworth died from pneumonia in the Fukuoka camp in Japan in December 1944. But Ms Buttsworth's mother did not learn of his death until almost a year later.

"I still have a few letters he sent to my mother and some cards from the prison camps. These were always optimistic, telling my mother he loved her and not to worry. He makes only one slight reference in his letters as to why he enlisted: 'I have a clear conscience somehow - you know how it is'," Ms Buttsworth wrote in a 2012 tribute.