Nothing moves in the Ukrainian city once known as the Soviet Union's 'capital of glass'. 

Kostiantynivka's streets, buckled and deformed from years of artillery fire, missiles and bombs, are deserted. Its houses lie crumpled in ruins.

The factories that gave this faded industrial titan its moniker – and forged Lenin's crystal sarcophagus and the ruby–red stars that still adorn the Kremlin – lie abandoned. Or so it seems.

'Look at the screen,' Volodymyr says, gesturing to live, full colour images from an observation drone that hovers hundreds of metres above in the eastern region of Donetsk. 

'It looks like an empty city – but it isn't,' whispers the 42–year–old Ukrainian drone pilot, who cannot be fully identified.

'Our people are there. The Russians are there. Nobody dares show their face. That's what war looks like now.'

Hiding from swarms of drones that map every inch of this war–ravaged hellscape, among the ruins and the foliage provided only during the summer months, Russian infiltration teams and Ukrainian defenders are engaged in a desperate fight that will decide the next turn of this war.

The Daily Mail was given rare access to the Seraphymy Unmanned Systems Battalion of the 104th Independent Territorial Defence Brigade in Donetsk last month.

Here we witnessed the battle for Kostiantynivka, one of four cities in the Donbas that make up Ukraine's 'fortress belt'. 

Logistically vital, the belt stands between Moscow and its stated war aim to seize this region – and collectively forms the backbone of Ukraine's remaining defences in Donetsk Oblast.

While many feel it is only a matter of time before Kostiantynivka falls (it has already been breached by up to 200 invaders), the manner in which Ukraine has harnessed drone innovation to slow Russia's advance may offer a blueprint for how it repels them completely from the three remaining key cities.

In short, the revolution happening here will determine if this will be the last great fortress Russia takes – and, if that proves to be the case, could ultimately force Vladimir Putin to finally enter peace talks.

Kostiantynivka is the stuff of science fiction. Within the 15–mile 'kill–zone', vehicles, heavy armour and tanks have all but disappeared in the past 12 months. 

Artillery, still vital, is heavily camouflaged and used sparingly. Too big. Too easily spotted. Here, where drones rule the skies, they often become 'weapons of self–destruction'.

Instead, men move in ones and twos, from foxhole to foxhole, cellar to cellar. Detection from above is death.

The second human activity is identified, the entire building in which it is spotted is brought down by drones. 

'People are like ants,' Volodymyr explains. 'They're hiding, crawling, constantly moving underground. The moment someone is spotted, 15 drones are on their way.' Shaking his head, he adds: 'It's a terrible war.'

But Volodymyr is not among the ants. Thanks to cunning Ukrainian innovation, he is piloting his hulking 17in bomber drone from 37 miles away in a secret location the Daily Mail was invited to.

On larger drones such as this, Kyiv has attached Starlink terminals to give them a secure satellite connection that is largely unjammable. 

It means bomber pilots who once sat within three miles of their machine have been moved out of the kill–zone.

This is a game–changer. Lest the peril for those who remain on the frontline needs spelling out further, beside Volodymyr's observation screen and a tablet showing the tactical map of the city sits a third monitor which we were not allowed to photograph. 

It carries the day's operational picture. A Russian soldier has been located in a house. That is now the target.

Reconnaissance crews, drone pilots and commanders coordinate the strike in real time. 

The operation unfolds in silence. The drone pilots continue talking over the radio. A bomber drone releases its munition. It fails to explode. The Russian soldier breaks cover, sprinting from the house into a patch of bushes.

A First Person View (FPV) kamikaze drone carrying a 1.5–kilogram high–explosive dives after him. 

The onboard picture rushes into the foliage – and disappears. There are no cinematic explosions here. The screen simply goes black. 

This is how soldiers meet their maker in the 21st century. Volodymyr is now free to go and make a cup of coffee. His radio sits within arm's reach. 

Whenever reconnaissance identifies another target in the ruins of Kostiantynivka, he returns to his workstation, takes control of his bomber drone and flies another mission.

This way of waging war is the brainchild of Mykhailo Fedorov, the recently sacked Defence Minister whose dismissal by Volodymyr Zelensky after just six months in post prompted nationwide protests earlier this year. 

In his previous role as head of Ukraine's Ministry of Digital Transformation, Fedorov ramped up drone procurement on an unprecedented scale in response to Russia's 2022 full–scale invasion.

It was here that the concept of the Drone Line – using unmanned systems as the backbone of a front held by too little infantry – received institutional backing. 

Given Ukraine has only a modest air force and a serious manpower challenge, the concept was to harness drones to preserve the lives of personnel and repel the Russians. 

The unmanned systems would be used to establish a kill‑zone through which the enemy cannot advance without sustaining heavy losses.

When Fedorov was promoted to Defence Minister in January, the Drone Line program surged drastically, as he pumped 90 per cent of the weapons budget (not including the vast arsenals supplied by the West) into robotic warfare.

In Kostiantynivka, this has manifested in its most extreme form.

Yet this city has not fallen. With Ukraine's increased drone capabilities, invaders are identified and liquidated almost instantly.

'What fascinates me is the war we're fighting now,' Serhii Kostynskyi, commander of the battalion, tells us. 

'The way we fought in 2022 and 2023 was terrifying. You spent your days being blanketed by artillery. The enemy never had to come within rifle range. They simply erased you with artillery and mortars. Then the tanks moved in. The Russians had an overwhelming advantage in artillery – it really was the First World War.

'Now it's different. Both we and they have an incredibly wide range of tools at our disposal.'

Within the kill–zone, infantrymen are scattered in teams as small as two or three. Hiding in dugouts and basements, they largely act as lookouts to call in drone strikes on any infiltrators.

Unmanned robotic vehicles support them with supplies and evacuate casualties. 

Giving them cover are pilots, also hiding on the frontline, who fly FPV kamikaze drones on gossamer–like fiber–optic cables. 

These drones, which have a range of about nine miles and cannot be jammed, are launched by a separate team of soldiers.

A year ago troops would drive into position, unload and speed away, but the proliferation of enemy observation and attack drones means that's now impossible. 

So the launchers enter in pairs, on foot. One pushes a handcart loaded with drones, batteries and ammunition. The other walks ahead, scanning the ground for mines with a drone detector around his neck.

Flying high above the kill–zone to avoid Russian electronic warfare are Ukraine's Queen Bee motherships, whose pilots are several miles behind the frontline. 

These carry swarms of smaller FPV strike craft and drop them up to 20 miles deep behind enemy lines.

Then there are the heavy bombers loaded with anti–tank mines and mortar shells connected to pilots like Volodymyr via Elon Musk's Starlink dishes. 

They use thermal imaging cameras to erase Russian armour and smash concrete fortifications while their crews are safely out of range. 

Protecting both men and machines are interceptor drones – ultra–fast, highly agile quadcopters equipped by AI tracking, which take out surveillance drones and effectively blind the enemy.

The Drone Line is stitched together with a constant layer of fixed–wing AI reconnaissance drones that map every inch of the battlefield and feed it live into a battle management system.

Software automatically flags shifting pixels on digital screens, instantly identifying hidden Russian troops and automatically sending the coordinates to the nearest drone crew. 

Russia possesses a roughly similar array of drones and this is an ongoing, evenly matched contest.

For the moment, Ukraine holds the advantage thanks to grassroots initiative and integration into Western technology – most importantly Starlink. 

It is little wonder the men of Seraphymy believe a day may be coming soon when men are all but removed from the battlefield. 

Volodymyr thinks soon every drone, not just heavy bombers, will operate through Starlink. Reconnaissance crews and FPV teams will no longer have to occupy exposed positions on the edge of Kostiantynivka's kill–zone.

Instead, he is adamant they will work from rooms like his, with coffee machines, reliable internet connections and dozens of kilometres separating them from the battlefield.

He adds: 'Within a year, infantry will all but disappear from the kill‑zone. Ground robots will carry weapons. Everyone will be sitting behind a control console, connected through Starlink, miles from the fighting.

'Watch what happens over the next six months… everything will be done remotely. That's the direction this war is heading.'

Despite Fedorov's untimely removal, investment continues to pour into Ukraine's drone units. 

The 104th Independent Territorial Defence Brigade is already in the final stages of raising a second unmanned systems battalion. 

Seraphymy, a territorial brigade, is one of the lowest rankings in the army, yet is receiving cutting–edge supplies. In just six months, the army is aiming to increase the number of drone crews sixfold.

Military expert Bob Seely, a partner in Ukraine–UK defence firm Trypillian, says: 'We are witnessing a significant evolution of warfare. Sadly not enough soldiers and politicians in the West understand this.'

Moving pilots out of the kill–zone has long been 'a Ukrainian priority' and as a consequence we are now seeing 'the rise of the machines', Mr Seely, a former MP and British soldier, adds. 

'It is likely that war in the future will be largely fought by decision–making machines – overseen at least on our side by humans,' he said.

'It's the quality and survivability of your machines that will dictate whether you win or lose.'

While observers marvel at Ukrainian advances, experts generally push back on claims that the infantry will disappear. 

Paraphrasing Mark Twain, Retired American Colonel Frank Sobchak, professor at the US Naval War College, said: 'Reports of the infantry being outmoded are greatly exaggerated.'

Noting how often before this has been falsely predicted, he adds: 'The infantry will always have a role on the battlefield, as there is no other element that can seize and hold terrain.'

While it is still unclear how NATO would fare in such a war, despite its vastly superior logistics and air power, the alliance is undoubtedly playing catch–up.

Ukraine is in the ascendancy but it has learnt this guarantees nothing. The pendulum could swing back as early as this autumn.

Russia is already rolling out technology it believes can jam Starlink. It is looking for alternatives to use itself offensively.

This is why Mr Zelensky's removal of Mr Fedorov at such a critical juncture is so troubling.

Now the widely respected General Mykhailo Drapatyi has taken over as Commander–in–Chief while former head of intelligence Yevhenii Khmara is Fedorov's acting replacement.

It must be hoped that they can quickly get to grips with this revolutionary battlefield as well as the Ministry of Defence, which spends more money than all the country's other ministries combined. 

The future of Kostiantynivka, and the rest of Ukraine, depends on it.