Every night when Les Drew came home, he would turn the corner and look at the four flagpoles in the garden, one for three of his brothers and his father who were away at war. A flag at the top of a pole meant one of them had returned alive. The flag for Ken was never raised. The three brothers and the father had all been in the Salvation Army. Ken transferred his musical skills from a Salvation Army band to the battalion band in New Guinea. But he was captured by the Japanese. He became one of the 1054 people - mostly Australian - who drowned when the Japanese prisoner-of-war ship transporting them was torpedoed mistakenly by an American submarine in 1941. The sinking was the worst disaster at sea in Australian history. On Monday, the descendants of some of those who died will meet in Canberra for what will no doubt be an emotional reunion. Back in April, the wreck of the Montevideo Maru was finally located more than 4000 metres down on the bed of the South China Sea. Les Drew said when the vessel was located: "I thought they had stopped looking." He and the other families had lived in an agonising uncertainty for more than eight decades when all sorts of rumours and wild speculation swirled. One false theory had been the ship had left harbour in New Guinea and then returned lighter in the water - prompting all kinds of speculation about the fate of the prisoners. Some doubted the vessel had even existed. But some doubts were dispersed in 2003 when a Japanese sailor who had witnessed the sinking told the ABC he had seen prisoners in the water. "They were singing songs. I was particularly impressed when they began singing Auld Lang Syne as a tribute to their dead colleagues. Watching that, I learnt that Australians have big hearts," he said. A little more certainty came in 2012 - 71 years after the sinking - when the Japanese government handed over thousands of documents about prisoners of war, including the full list of those on the Montevideo Maru and who had drowned when it was hit. For the families, knowledge has brought some relief. The wreck is now an official war grave. Ken Drew's great-niece Rebecca Mills was in tears when she heard on the radio the ship on which Ken had died had been detected on the ocean floor. "We just jumped in the car and went over to grandpa and he was overwhelmed," she said. "It's like he could start to heal again." The brother, who now lives overlooking Lake Tuggeranong in Canberra, had given up hope of ever knowing where his brother had died. "We finally knew his resting place," Rebecca Mills said. She had become obsessed with the fate of her great uncle after she discovered a box of family pictures and letters. Every one of the descendants has a similar story of loss and then of some sort of reassurance, often from talking to each other. They formed the Rabaul and Montevideo Maru Society (Rabaul was the town in New Guinea where some of the Australian prisoners were captured). The society's chairwoman Andrea Williams' grandfather and great-uncle were on the Montevideo Maru. For her, finding the wreck was an "enormous, enormous event". "Monday will be a special occasion to reflect on all those who died in this disaster and honour their courage and sacrifice," she said. "It's an enormous comfort to all the families to know where the men rest. It honours their memory." Mark Dale is the great-nephew of three brothers who died. "The three boys enlisted on July 10, 1940 with sequential serial numbers," Mr Dale said about his relatives. One of the lads was too young to enlist - so he lied about his age. "Their mother found out a week later when they arrived home in uniform - it was not a happy house that night," he said. The current chairman of the Australian War Memorial and former Labor leader Kim Beazley's uncle, the Reverend Syd Beazley, died in the tragedy. "Finding the site of Australia's most devastating loss at sea will help heal Australia's collective memory for generations," Mr Beazley said. "This has solved a Second World War mystery and my family's history." When the ship was located, the Prime Minister said he hoped the discovery would bring a "measure of comfort to loved ones who have kept a long vigil". The families hope Anthony Albanese will be there on Monday.