On the night that 84-year-old Kiyoshi Uehara thought for certain he would die, the sky above was a blanket of primrose purple freckled with endless stars, but there was no moon. “When death is near, you stop worrying about how it will come and start noticing the small things, like the night sky,” he says. It was August 22, 1944, and a 10-year-old Kiyoshi had been drifting for six hours off the frigid north-western coast of the East China Sea on a plank of cedar wood no bigger than a cupboard door when this realisation hit. Part of an emergency evacuation convoy from Okinawa to Nagasaki, the ship he was on, the Tsushima Maru was torpedoed by the RSS Bowfin, a US Navy submarine.

The civilian ship was meant to act as a safe passage for Okinawa citizens. It had been carrying 1,661 evacuees – women, children and the elderly – when it was attacked shortly after 10pm. Of these, more than 1,000 children would lose their lives; only 59 people survived the attack. The battle of Okinawa would commence eight months later, but this would be the first show of force by the Americans – to innocent, unarmed civilians nonetheless.

Masayoshi Oshiro, 85, is slowly losing his mind. “Over the years, I have forgotten the faces of friends, family and even where I live sometimes. But the war – that’s different. I remember the war as if it happened a few hours ago,” he says with a slight smile. It was a quarter after one on a dusty February afternoon in 1943 when Masayoshi realised his life would never be the same again. After his school’s headmaster sounded the bell for an emergency assembly, the students saw neatly packed bamboo poles at the front of each class line. “We all thought we were going to play games. None of us knew that we were preparing for a lesson on how to spear American soldiers in close combat,” he says. Having bombed Pearl Harbour two years prior, the Japanese government was certain that US retaliation would come. But not willing to sacrifice troops or leave the mainland in peril, they decided to mobilise ordinary citizens – many as young or even younger than 11-year-old Oshiro. What ensued was a two-year war preparation programme for the teachers and students alike.

Apart from learning how to effectively shave off the ends of a bamboo pole using a home knife, the programme included daily four-hour sessions in which students would bayonet effigies of American soldiers made out of gunny sacks filled with hay. “I felt empowered because I was told I was doing this to protect the Emperor of Japan. What I didn’t know at that time was that the Emperor of Japan had no plans to protect me,” he says.

Whenever Kiku Nakayama, 83, talks about the war, it is in soft, hushed tones. It’s as if the spectre of war that continues to hover around her might come to life again if she dare raise her voice, as if talking just one decibel higher might reawaken demons she has fought hard to put to bed over the years. “Do you know what is worse than dying in a war? It is surviving it. Because every other day after that, you think about it,” she says. At only 16 years old, Kiku was conscripted to be part of the Shiraume Nursing Corps, a female medical unit put together by the Japanese army that tended to sick and injured soldiers.

The unit comprised of 56 students of the Dai-ni Koto Jogakko, an all-girls high school. Twenty-two of the students would die in the following few weeks because of the fierce fighting. Realising a lack of medical staff on the island, the Japanese government mobilised schools around Okinawa to get students to serve as nurses and medical staff. Kiku was into her 18th day of medical training when she and four other girls were asked to serve as medical assistants to a doctor at a cave near Naha City. “Some soldiers came in with their guts spilling out, some had their entire faces burnt away because of the shrapnel. It was truly hell on earth, in every possible way,” she says.

Masako Nakazato was 18 years old on August 22, 1945, when she was handed a knife and told to run it deeply and swiftly across her flesh just above her clavicle. A deactivation order had been sounded by the American troops a few hours prior and Japanese soldiers began spreading rumours that Americans would rape and burn the women they found. Hundreds committed suicide by jumping off cliffs or blowing themselves up with grenades handed to them by soldiers.

There are even accounts of family members beating their children to death. In the Chibichiri-gama or “mass suicide” cave located in the middle of Yomitan village in Okinawa, 83 civilians, mostly families, killed themselves on April 2, 1945, for fear of being captured by US soldiers. Today, the cave serves as a memorial to the families. Masako was in a similar cave on the northern side of the island when a nurse handed her the rusty knife. “We had run out of cyanide and grenades so the knife was the only solution. A few other ladies had used it to kill themselves so by the time it reached me, it was drenched in blood,” she says.

Hacksaw Ridge, a place of intense fighting during the battle of Okinawa, is now a tourist attraction.

A view of Okinawa from the infamous Hacksaw Ridge, the site of one of the bloodiest battles in the second world war.