The story no Hollywood scriptwriter could make up: He spent 491 days stranded in the kill zone under Russian fire - and had to amputate one of his legs. Then he became the first soldier ever evacuated from a battlefield by a drone...

After enduring 491 days in the kill zone and forced to amputate his right leg with a blunt knife after losing his left to frostbite, Kostiantyn Vlasenko received the call he thought might never come.

For the previous 231 days, the Ukrainian infantryman had been alone, hiding within a cast-iron furnace in an abandoned school, after his only comrade, callsign 'Baski', had been killed.

He and Baski had found refuge here last winter after a cramped underground concrete drainage pipe where they had spent their first eight months flooded, forcing them to flee.

But there were so many enemy aircraft around this position in Kharkiv region, eastern Ukraine, the sky had turned 'dirty' – or saturated – making their evacuation impossible. A Russian drone tracked their location and killed Vlasenko's comrade on his 50th birthday – leaving Vlasenko with severe injuries. Now, he was told, a rescue was finally going to be attempted.

'It's being planned,' his commander said over the radio. 'Everything is practically ready. There are just a few finishing touches.'

The next sentence left the grizzled 49-year-old infantryman dumbstruck. 'They're going to drop instructions to you today,' the commander added.

'What instructions?' Vlasenko whispered to himself. 'Don't I know how to crawl out of a hole, damn it?'

He was certain they would send an unmanned ground vehicle, or burst through on a quadbike, as Ukraine usually does to evacuate casualties on the frontline.

But soon he had the answer. A drone dropped a sealed bag to his position, which contained a nylon seat, rope, carabiners, and a phone loaded with a video detailing what he must do. As he watched the film, it suddenly dawned on him what his superiors had planned.

'I realised it was going to be an aerial drone, because in the video he [the drone pilot tasked with saving him] was saying, 'I'll descend, and when I land, you must do this and this…'

'It was going to land and turn off its motors so I could crawl underneath.'

On October 4, Ukraine's 92nd Separate Assault Brigade sent a heavily modified bomber drone to Vlasenko's position in Petropavlivka to carry out the first unmanned aerial evacuation of a wounded serviceman in military history.

Incredible footage shows Vlasenko strap himself to its underbelly, giving a thumbs up to its camera before it rises 400ft (120 metres) in the air and flies him 11 miles to safety.

It was flanked by a fleet of three Vampire drones to fight off the Russians, with one of them taken out by the enemy.

Now recovering in hospital, Vlasenko, callsign 'Kostya', revealed the extraordinary story behind the evacuation to Ukrainian journalist Yuriy Butusov.

Wearing a Gurzuf Defense cap – a nod to the company which made the drone that rescued him – he says of the rescue operation: 'I have no words… A wonder. It is a miracle.'

Vlasenko's eyes are still sunken and his skin deathly white from 16 months on the front line, nearly all of it spent underground or in darkness.

He fidgets anxiously, stroking his wispy grey beard as he details his extraordinary story from a wheelchair in hospital.

Having grown up in Volodymyr Zelensky's hometown of Kryvyi Rih, central Ukraine, the father of one was working as a truck driver when the full-scale invasion began in February 2022.

After driving to the draft office and demanding to be signed up, he was given a position with the 2nd Battalion of Ukraine's 30th Mechanised Brigade.

On June 2 last year, Vlasenko was ordered to evacuate an injured comrade, who had stepped on a petal mine – a Soviet-designed landmine – and take over from them at a position in a concrete drainage pipe.

It was here that he met Baski. A hole in the middle of the pipe had been opened up that led down into an underground 'shelter' – a dark hole barely big enough to sit in.

Vlasenko and Baski would take it in turns to hide in the 'shelter' while the other kept watch in the pipe above. Ukrainian drones would make food deliveries to ensure they had enough to survive. They should have been rotated out from their positions after two months, but soon Russian Mavic drones filled the skies above, making it impossible to leave.

An attempt to relieve them failed. 'They tried to replace us once, but they didn't make it,' he said. 'Later, other brothers-in-arms went out just to retrieve their bodies, but they couldn't make it either. They couldn't recover them. So I said there was no need to come for me. Better that I die alone than more people die.'

After spending eight months in the pipe, it flooded on February 14 this year.

'We crawled out and were already soaked as we moved', he said. 'A hard frost set in again then… I had no strength left. We were already so weak.'

The pair reached a ruined school undetected and radioed in supplies to their location – but soon a Russian reconnaissance aircraft spotted the deliveries from Ukrainian drones. 'Then they started dropping munitions,' Vlasenko said.

'I was hit in the leg, but my feet were so frostbitten that I didn't even feel anything strike me. Basically, my left leg was shattered. I could still stand on my right. Then our guys flew in and dropped food, and I twisted my right leg while going to collect it. After that, I couldn't move normally at all.'

Desperate with hunger, Baski climbed out to collect the food. But an enemy drone flew in and hit him.

Vlasenko got to him but, with no torch, could not make out his injuries in the dark. But all night he could hear his comrade's groans, unable to help.

'He was just moaning… He couldn't really say anything… I pulled him closer to me, as best I could. Then he went quiet…

'By morning, my brother-in-arms had died. I couldn't save him. He died on his 50th birthday. He never got to celebrate it. God gave him a gift and took him.

'I was left alone on February 16. When it began to get light, I covered him up.'

His position compromised, Vlasenko stood on his twisted leg, grabbed his rifle and any supplies he could carry and tried to escape. As he did so, he heard an explosion nearby.

'It turned out they were warning me,' he said. 'Later, they dropped a speaker, playing a recording telling me to surrender.'

The speaker told him: 'Brother, we know you're here. Believe me, your comrades won't save you.

'You heard the explosion. The next one could be aimed at you. We don't want to kill you.

'Put a can or a bottle on the windowsill, and we'll know you're ready. A white light will guide you [referring to a drone]. Then captivity, the exchange pool, and home. Yes, exactly – home.'

Instead of doing as they asked, Vlasenko responded with the now-infamous phrase of defiance used by the defenders of Snake Island, the tiny spit of land captured by Russia in early 2022: 'Russian warship, go f*** yourself!'

'It's a pity they couldn't hear me,' he joked.

He radioed his commanders, who sent in drones to destroy the speaker, but they were unable to locate it.

'Twenty minutes later, their big drone flew in,' Vlasenko said, referring to a Russian bomber.

He curled up on his side, clenched his teeth and waited for it to drop its munition. 'Then came the explosion,' he said. 'What an explosion… I thought I was dead. It was dark.

'I opened my eyes, and it was still dark. I wondered whether I could still see. But the fact that I could feel grit in my teeth meant that I was alive.

'And that damned speaker kept playing…'

Vlasenko managed to crawl inside a cast-iron furnace that he spotted amid the ruins.

'There was a little opening… I don't know what angel pushed me in there,' he said.

Seconds later, the drone dropped a second enormous munition. 'Everything started collapsing on to me,' he said. 'That was it. I thought I was… But I felt the same thing again: grit in my teeth. So, I was alive.'

This is where he stayed for the next eight months. His comrades would send food and medicine by drone into the school's ruins; he would climb out of the stove, collect it, then climb back in.

He would continue to provide combat surveillance, reporting back what he could see and hear of enemy movements.

While lying there, he noticed how the human body 'pushes foreign objects out by itself'.

'Pieces of shrapnel started falling out of me,' he said. By April, though, his wounded and severely frostbitten left foot developed necrosis and eventually fell off.

That, however, wasn't the end of his gruesome ordeal.

The next month his right leg, which he had twisted, went completely numb at the ankle and developed gangrene. Vlasenko describes how it started 'dangling'. 'The lower part of the leg was just hanging there,' he said. 'The more often I crawled out to collect supplies, the more it pulled on the bone. The skin was peeling away.

'I realised I had to cut it off. I knew it couldn't be saved any more. I had wanted to keep at least one foot. But it didn't work out, so it didn't work out.'

'I put it on a brick and took a knife. Tears were flowing, but I had to cut. So I cut.'

As the weather began to warm, he remembers seeing hundreds of big orange and black butterflies flying where his severed legs lay.

For months, the only company he had was the radio as other positions phoned in '450' – meaning 'all quiet'. He said: 'When I heard the men at other observation posts reporting '450, 450' – I thought, 'I'm still with someone…'

'And that was it. Silence again… I waited every hour for a report. It was happiness for me to know I wasn't alone, to hear someone. I went wild during that time… It was very lonely.'

But his men did not abandon him, sending him chocolates, sweets, tea and cigarettes by drone. 'They spoiled me, so to speak, so I would at least have a little joy, something to distract me,' he said. 'My wife sent a parcel. They packed it up and dropped it to me. What my wife sent was a Stephen King book: The Outsider.' It surprised Vlasenko, who said he didn't realise his wife Tetyana had noticed what a huge Stephen King fan he is.

He survived those many days thinking of his daughter, Khrystyna.

'I hadn't given my daughter enough attention,' he said. 'Maybe it was the feeling that I wanted to change something. A thirst for life… But I had also already decided that I was dead.'

Then, about a month ago, his comrade, Sergeant Lysyi, radioed and said that his rescue was being planned.

He received the instructions, and soon the drone arrived. As it hoisted him into the air, Vlasenko said he was afraid of being dropped in a river, because he can't swim. During his flight he spotted a Ukrainian drone going the other way with supplies for troops. 'That was something too: seeing it fly past,' he said.

'I want to thank everyone… Everyone who did so much for this,' he said. 'I don't even know all of them, but I want to give them a piece of myself. I am so very grateful to them.'

Despite his extraordinary survival, Vlasenko is uncomfortable with his newfound place in history as the first-ever soldier evacuated by aerial drone.

'I don't like being first,' he said. 'I prefer being second.'