Bradley Cooper as US soldier Chris Kyle in the film American Sniper. The regulars greet the old digger by his nickname, Robbie, when he arrives with Miki, his wife. Florence, the Chinese woman who runs the dance with her husband, beams at him and sings his praises. Robbie has "a heart of gold", she says. Others chorus agreement, and line up between dances for his famous neck massages. "He's very good - and never charges," says Florence. She thinks he has healing hands. In his other life, healing wasn't part of the job description. In fact, in all of modern warfare, few were more fatally efficient than this kindly grandfather. No one knows just how many dozen enemy soldiers he killed in eight bone-chilling months in Korea, except the man himself. And he's not saying much. Ian "Robbie" Robertson was born in Melbourne in 1927. His mother toiled over a boot-stitching machine from age 14 to 74. His father had been a teenage rifleman and bugler wounded at Gallipoli. One uncle was killed at the Anzac landing in 1915; another won a Military Cross as an airman in France. The family was self-employed but not wealthy.

Australian soldiers during a moment of respite on the front line in Korea, 1950. Credit:Alan Lambert On weekends the men used to go shooting. When Hollywood made a film, Enemy at the Gates, about a sniping duel at Stalingrad between a German marksman and the Soviet propaganda hero, "noble sniper" Vassili Zaitsev, the opening scene showed Zaitsev as a child, shooting a wolf in his native Siberia. Zaitsev - famous for shooting hundreds of Germans - was a skilled hunter before joining the army. It was the same with young Robbie Robertson, and a lot of other Australian and American snipers. Jude Law as a Russian sharpshooter in the film Enemy at the Gates. Growing up in the Depression in the struggling northern suburbs, the boy learned to shoot at a young age. The countryside close by was crawling with rabbits, which were meat and money for battlers. Rabbit traps, ferrets and a .22 "pea rifle" meant survival as well as sport.

Robertson's father was a crack shot - he had been a sniper at Gallipoli - and his uncles were good hunters. They taught the kid to stalk, freeze and watch, scanning the ground until he spotted a rabbit by the shine of its eye. He had a keen eye, a steady hand and lots of practice. A head-shot rabbit could be eaten or sold, a gut-shot one was dogs' meat and its skin worthless, so he had to shoot quick and clean. Two Diggers bring in a wounded Korean child for medical treatment. Robertson went to Northcote State School, then left Collingwood Tech at 13 to be a carrier's "jockey" on a truck, working around the boot trade. Later, he was a storeman. In 1943, at 16, he almost bluffed his way into the army - which would have meant fighting in New Guinea - but the recruiting sergeant told his father, who told Robbie that if the Japanese invaded he should be home to protect his mother and sisters. He finally enlisted when he was 18, missing the end of the war, and was sent to the occupation of Japan in 1946. If communist North Korea, tacitly backed by the Soviet Union and China, had not invaded South Korea in June 1950, Robertson might have served out his time without firing a shot in anger. But when the United Nations agreed to immediate retaliation by its members, led by the US, Australian troops were among the first sent to Korea to join a thinly veiled struggle between the world's Cold War superpowers. Once China joined North Korea, the UN "police action" would become a three-year war costing more than a million lives, including 33,000 Americans and 339 of the 18,000 Australians who served there.

In Japan, Robertson had been working as the battalion photographer, but with war looming he was made a sniper because he was one of the 10 best marksmen among the battalion's 600 troops. It was like being picked for the school sports, but more dangerous. He went to Korea in the autumn of 1950. Days were crisp but nights freezing, a taste of the cruel winter ahead. If an enemy bomb or bullet didn't kill you, the standard-issue Australian uniform might: it was hopeless for northern winters. To survive, diggers had to beg, barter or steal extra gear - woollen caps, gauntlets, mittens, waterproofs - from the Americans, who had plenty of everything. Snipers were issued with a modified version of the venerable Lee-Enfield .303 rifle used by British Empire troops since the Boer War half a century before. The sniper model had a small telescopic sight and a heavy barrel, but otherwise was little different from a million others lugged by Allied infantry in two world wars. Robertson could group 15 rounds in a space smaller than his fist at 300 metres, hit a target the size of a man's head at 600 metres, and was confident of hitting a man from 800 to 1000 metres if conditions were right. Not that long-range marksmanship helped much in his first engagement. It was their first week in Korea. Robertson and his first sniper partner, a South Australian called Lance Gully, were escorting their commanding officers on reconnaissance - driving ahead in a Jeep to "clear the ground".

It meant they would draw enemy fire first, protecting the officers. They stopped their Jeep and split up to scout on foot. Minutes later, Gully surprised 30 or more enemy soldiers hiding in a ditch. They showered him with hand grenades. He jumped in the ditch with them to avoid the blasts, then backed out of it, firing as he went. If he missed he was dead. After nine shots for nine hits, a grenade burst wounded him. When he heard firing, Robbie ran to help. He saw a flap of his mate's bloodied scalp hanging off his head and a crazy thought struck him: "Lance looks sharp with that Mohawk haircut." The wounded man screamed: "There's a million of them in there, and they're all yours." Years before, an old digger had told him how to survive superior numbers at close range: Keep both eyes open, point and snap-shoot, count the shots and reload after six. And be aggressive: give them time to think and they'll kill you...

He ran up to the ditch, shooting anyone who opposed him, squeezed off six shots then ran back, jammed in another clip and ran at the ditch again. He did it six times, until no one was left alive. Gully had shot nine. The rest of the jumble of bodies were down to Robertson. He could hardly believe he was alive, unhurt apart from a furrow across his wrist left by a machine-gun bullet. It was a miracle. Officially, it was a "skirmish" at the start of what historians call the Battle of the Apple Orchard. Lance Gully returned to the line later, but the shrapnel in his body made him too sick to stay. So the boy from Preston got a new sniping partner, a reputation and the first of a lifetime of recurring dreams. They call Korea the forgotten war, but the old digger can't forget it. "Every battle happened yesterday," he says, his voice serious. "When people are trying to kill you, it concentrates your mind. You don't leave it behind."

Retired Warrant Officer Robertson easily passes for a happy man - a law-abiding, patriotic, devoted husband and grandfather with a lively mind hidden behind hearty humour. But only a fool or a psychopath could forget the things he's seen and done in the line of duty, and he is neither. Sometimes, when he closes his eyes he sees the dead, and they are many. The memories turn into dreams when he sleeps. "You relive situations based on what happened," he says. "You are always going on to attack another hill. All the strain of it comes back..." His voice trails off. He is sitting on a couch in the spotless living room of the couple's spotless 1960s brick veneer, in a street that could come from a Howard Arkley painting. The floorboards have been stripped and polished and every surface gleams, but there is a pleasant clutter of souvenirs. On the television set is a tiny teddy bear and a calendar with the words: "Show kindness to others." Robertson's iron-grey hair is worn in a crewcut and his eyes are piercing. He wears glasses only when he has to read, looks tanned and fit for his age and still has the restlessness of a man of action. The house is full of evidence of various hobbies - since retiring he has learned not only massage, but riding, saddlery and military drumming. He made the elaborately tooled Western saddle that sits on a stand near the front door. His study is crammed with reference books, military histories and biographies.

He is a good talker - but not about himself, for fear of being branded a "big noter". He keeps quiet about his wartime role except with a few ex-army friends. "It's a bit like belonging to one of those lodges," he deadpans. "Nobody likes snipers, you know," he adds. "I'm not ashamed of it, but I don't want to be called a murderer by some bleeding hearts." He doesn't want to be cast as "some sort of heroic figure", either: "I'm not. We just lived it." He finds it hard to explain what it was like - the fear, boredom, filth, cold and horror, and the guilt-edged elation at surviving - to anyone who wasn't there. "It's like a seamstress talking to a bricklayer - there's nothing in common." Fragments of the real story emerge haltingly, and over several days. His past hasn't caused him much trouble "because I didn't tell anyone", he says. But a few times during the 30 years since he left the regular army, someone told "the people I worked with [about him being a sniper] and it would rankle for a while. They'd call me things like 'trained killer'. I'd tell them it was a long time ago."

It's a sore point. He jokes he doesn't want to be seen as "Uncle Vinnie in the Mafia" - some sort of cold-blooded killer for hire. Snipers often had to shoot in cold blood - rather than in the heat of an enemy assault - but that didn't make them murderers. They were doing their sworn duty, under legitimate orders and the conventions of warfare, against an armed enemy trying to kill them. Still, sniping is the dark art of conventional warfare. In America's gun culture, it attracts a fringe celebrity status that supports a growing list of books and websites. Australians are more ambivalent. In World War I, a Queensland kangaroo shooter, Trooper Billy Sing, became a household name for reputedly killing more than 150 Turks at Gallipoli. He was later decorated for bravery but fame turned into notoriety in peacetime. He was called "an assassin" and "a murderer" and died divorced, broke and alone in a rented Brisbane room in 1943. Robertson fears being demonised the same way. Snipers were no more "murderers" - or "heroes" - than pilots, artillerymen or army cooks. They were just more cost effective, with the best snipers averaging about 1.3 rounds per "kill".

"But we weren't a lot of Hollywood macho idiots carving notches in our rifle butts," Robertson says fiercely. "We were never body counters." Apart from the first furious fire fight he so miraculously survived, Rambo it wasn't. It was dirty and dangerous and bitterly cold. They called it "mobile warfare", with the Allies pushing North Korean and Chinese troops from ridge to ridge in one of the bleakest battlefields in the world. In that winter of 1950-51, temperatures plunged far below freezing, oil froze on rifle bolts, frostbite was a constant threat. They went weeks without a bath, and wore pyjamas underneath their uniform and scarves, balaclavas, waterproof coats and heavy American "pile" caps. The hills "were as steep as pyramids". Robertson's pack was heavier than most: he always carried two days' rations and 300 rounds of ammunition, in case he was caught outside the lines. Climbing hills in the snow, wearing several layers of clothes, made him sweat. And sweat froze. Every few hours, he had to scrape together some twigs on the lee of a ridge, get a fire going with lighter fluid, take off his sodden boots and "cook" them next to the flames, then whip off his wet socks and swap them for a stinking pair kept under his jacket to dry from body heat. To prevent frostbite he would rub his feet, then jam on the hot boots. "Every night we'd have to dig through 18 inches [45 centimetres] of ice to reach unfrozen earth to sleep in. In the mornings we couldn't wake blokes up because they'd be down with hypothermia." They slept with their rifles to stop the metal freezing. If the barrel froze, fingers would stick to it, just as their lips stuck to metal mugs.

Robertson had two cameras in Korea, and often had one slung around his neck. He took a lot of photographs of fellow soldiers - now held by the War Memorial in Canberra - but few action shots. When there was action he shot with a rifle, not his Canon. He saw scenes he refused to photograph. Once, they found a tiny church full of bodies. Men, women and children had been beaten to death. "I took one look and walked out. They [North Koreans] had been torturing the kids in front of their parents to make the parents 'confess' to something, then they'd kill all of them. We found the kids' bodies with their arms and legs broken." They found villagers bound hand and foot and buried in latrine pits to die. In other places, victims were trussed with wire looping their necks to their legs so that they strangled themselves. "I can't forgive the communists for what they did," he says. After 54 years, memories petrify into a series of frozen moments, like random snapshots from an old album. He remembers not only brutality but acts of courage and kindness. He talks of his battalion rescuing a regiment of American paratroopers, who were under siege, almost out of ammunition and getting ready to die when the Australians arrived.

"When the Yanks saw our big hats they let out a cheer because they thought we were Texans!" he grins. "We sailed into the enemy so hard they withdrew. The American commander was so grateful that when he went home he fenced off part of his ranch, and put up a sign and an Australian flag." At Pakchon, a raft of wounded Australians capsized crossing an icy river. Robertson saw a digger with a jagged piece of brass shell case hanging from his belly struggle through the icy water to save another wounded man. Both should have died but both lived. At Chongju, he saw five Korean children, terrified, caught in the battlefield. "I called to them in Japanese, 'Come here', and they ran over to where our mortars were. The mortarmen got the kids to hop in the gun pits and gave them their own helmets to protect them. There wasn't enough room so the two mortarmen jumped out and took their chance in the open. I remember those little faces looking up at them - thankful, with a bit of reverence." He remembers a soldier called Carl Whittaker, last man standing of 20 diggers mowed down during a bayonet charge. Instead of going to ground, Whittaker shouldered two rifles, picked up his wounded mate and carried him to shelter behind a paddyfield wall - then continued the charge on his own. Bullets hit the ground all around him but he kept going. While the enemy was distracted by the lone Australian running at them, a reserve section was able to run across and take the enemy position. "He was worth two Victoria Crosses," says Robertson. "But he got nothing but a bawling out for stopping to pick up the wounded fella. It was against orders."

The old soldier is a methodical man. Keen to see Good Weekend properly briefed, he takes two pages of A4 paper and a sharp pencil and makes neat columns of terse notes about the Korean campaign. In a column headed winter he begins, "North wind from Siberia and Manchuria - howling gale - covers the rivers with ice in one day", then grows long and detailed, moving from weather and clothing (he lent his fur-lined flying boots to everyone who did sentry duty) to the problems peculiar to snipers: "Laying up in hides [was] a problem - frozen stiff - low circulation danger. Fingers cracked, knuckles skun and infected, knees bruised and aching from slipping in icy slopes. Breath freezing on upper lip, chilblains, nose chapped and raw..." It is thorough but there is no devil in the detail, no insight into the thoughts of men who had to keep still for hours, watching and waiting to shoot or be shot. It skirts the unspoken questions of 50 years: What was it like to hunt humans? How many did you kill? He still has too much field craft to leave himself exposed. He won't bare his soul - deflecting questions with half-answers and digressions. He handles the subject his way, telling a story about what he calls his "private war" at a place they called Hill 614.

It was late winter, early 1951. He followed the same routine he had dozens of times. At dawn he crawled into the open, forward and to one side of the Australian line. He found a depression away from any landmark or reference point - "never get behind a tree or a big rock" - and fired an incendiary round across the valley so he could adjust his rifle sights to the distance, about 1000 metres. Then he inched to another spot nearby. He was filthy with mud, and blended in with rocks and patches of melted snow. He rested his rifle on his pack and waited his chance. Through the telescopic sight he could see enemy soldiers with binoculars scanning his hillside. He aimed at one - putting the vertical "post" of the sight on the point of the chin - but did not fire until they turned to talk to each other, in case they saw a movement or rifle flash that would give him away. The rifle's recoil meant he didn't see a bullet strike, so he could not be dead certain he had hit a particular target. A near miss meant his quarry would duck and hide, anyway. He was never sure which bullet was fatal. He found this element of doubt oddly comforting. At Hill 614, in between scouting sorties, he spent hours alone on the hillside, methodically picking off his marks, one by one. He called it "switching them off". After each shot he would work the bolt gently to lever in another round, then lie stock still. The Chinese had a proverb: Kill one man, terrorise a thousand. It was true, and it meant that each day, with each death, his job grew more dangerous.

All snipers were hated, good ones were feared. The better he shot, the more desperate enemy officers would be to kill him to stop the loss of morale. This is the sniper's dilemma: the more enemies you hit, the more return fire you attract and the more likely you are to die. Call it a Catch .303. His only chance was to melt into the landscape. To make sure his muzzle blast didn't disturb grass, leaves or dirt. To avoid any quick movement. To resist the temptation to hide among trees and rocks that would attract artillery fire designed to deafen or maim if it didn't kill outright. If you held your nerve, it was safer in the open. Sometimes he wondered what they called him. Feared snipers were given names by the enemy... At the end of a week, the Australians took the hill with a bayonet charge, led by a heroic figure called Len Opie, who took several strongholds single-handedly. Robertson ran up to the enemy position he'd been shooting at earlier that day, and saw something he never forgot. Where he had been firing, there were 30 bodies. One morning's bloody work. "Just one morning," he repeats, shaking his head. "And I'd been there all week. I got a feeling of horror. I never did the arithmetic.

I still don't want to." The Chinese did do the arithmetic. A few months later, in April 1951, a mortar opened fire with pinpoint precision at the spot where Robertson and his sniper partner were. It was obvious the mortar had worked out where the snipers should be in relation to their platoon. First the explosions burst his eardrums, then shrapnel ripped through his right hand. By next day it was "the size of a pumpkin". Before they shipped him to hospital in Japan two days later, he handed in his binoculars, compass, watch and rifle to the quartermaster. He would return to Korea much later, as a platoon sergeant, but his sniping days were over.

In 1952, he returned to Australia to shoot in the Queen's Medal target shooting competition, and ran second. While he was there, two old diggers took him to Preston RSL, in the suburb where he had grown up. He had been wounded three times under fire, and had accounted for more enemy soldiers than he cared to think about. But the man on the door wouldn't let him in - on grounds that "Korea was only a police action, not a real war." Years later, the same RSL branch asked him to join. "I told them to stick it up their arse." There are postscripts to his story. He married his Japanese sweetheart, Miki, brought her home to Australia and raised three daughters. He went to Vietnam in 1970, and came home a wreck - a victim, he thinks, not of Agent Orange but of Russian toxins used by the Vietcong. He retreated to a caravan on a bush block for months, and thinks he would have died there if it hadn't been for his faithful dog, who barked at him every morning until he took him for a walk. He has been a firearms instructor but has never been hunting since Korea. "I would hunt to feed myself but never for sport," he says.

He learned to ride and joined a Light Horse historical re-enactment group that takes part in parades. He still rides. Tomorrow, as in recent years, he will ride in Melbourne's Anzac Day parade in Light Horse uniform on a borrowed police horse. His own horse is too old to use now. He feeds him every day and dreads losing him. When his other horse - this one's mother - was injured several years ago, he knew what had to be done but couldn't bring himself to do it. The rifleman who once killed 30 men before lunch paid a veterinary surgeon to give his old mare a lethal injection. This article was first published in Good Weekend on April 26, 2004.