Stand on the railway embankment near Hostomel and look north-east and the story of Russia’s rout in the Battle of Kyiv comes together.

Three kilometres away you can see the village of Moschun, the site of a big battle and just south of it are the woods where Oleksandr Konoko, a battalion commander, described how, armed with anti-tank weapons, small groups of his men advanced to encircle the Russians.

It was at Moschun, and in the other suburban towns and villages north-west of Kyiv, that after a month the Russian ambition of capturing the Ukrainian capital sank into the area’s boggy wetlands.

The Russian attempt to take Kyiv was defeated by a combination of factors including geography, the attackers’ blundering, Ukrainian ingenuity and modern arms — as well as smartphones: used for the first time in military history as weapons powerful in their own way as rockets and artillery.

Moscow’s forces were thwarted, too, by pieces of foam mat — the Ukrainians call them karemats — costing as little as £1.50. The mats prevent Russian thermal imaging drones from detecting human heat. “We held the karemats over our head”, said Konoko, explaining how his men moved stealthily in tiny groups at night.

In that way soldiers armed with anti-tank weapons supplied by the US, Britain and others could sneak up on the Russians, fire their deadly and accurate missiles and then slip away.

Beyond the north-western outskirts of Kyiv before Hostomel, 30km from the city centre, lies a belt of forest. By the side of the road and at strategic junctions are massive trench and fortification systems which the Ukrainians began building immediately after the Russian invasion began early on February 24.

Here too, somewhere in the forest, are the missile systems that kept Russian planes out of Kyiv and shot down incoming missiles. The Russians were unable to destroy these air defence batteries at the beginning of the war, an important failure. But, prioritising the capital, Ukraine did not have air defences for other towns.

Other failures in those first days compounded Russia’s overall defeat on the outskirts of the capital, said Serhii Kuzan, chair of the Ukrainian Security and Cooperation Centre, a think-tank.

The Russians failed to knock out important parts of Ukraine’s military infrastructure, such as Kyiv’s air defence system, at the very beginning of the campaign, he said, meaning their campaign quickly ran into trouble. Commanders of different units continued to follow their original orders, even though events were not going to plan, thus compounding problems which arose as Ukraine’s military rose to the challenge.

Ukrainian forces have undergone profound reforms in recent years and unlike the vast majority of Russian army officers, thousands of their Ukrainian counterparts have battle experience from the eight-year war in the east. When they ran into problems, says Kuzan, Russian officers could only refer upwards in an old-fashioned, bureaucratic way while the Ukrainians were able to adjust to rapidly changing circumstances.

Konoko’s story exemplifies this. Sitting on his karemat in his HQ in Kyiv, his pistol on the coffee table and his Kalashnikov propped up by the sofa, he explained that he had been wounded several times fighting in the east after the war began in Donbas in 2014, where pro-Russian militants and Russian forces carved out two breakaway states.

He then retired to run a market garden. When the Russians attacked, he and his friends, all Donbas veterans, volunteered to join the new Territorial Defence Force. Its aim is to release soldiers to go to the front while leaving others to perform duties behind the lines.

They were assigned to guard checkpoints, said Konoko. But he had not put his potatoes aside for this.

“I have got a lot of experience,” he said indignantly. Very soon his newly formed unit, a combination of veterans and highly motivated younger men, left for Moschun, which had been occupied by the Russians. The unit was also transferred to the command of the regular army. Today the battalion consists of 725 men.

According to Kuzan, the recent military reforms and a new generation of battle-hardened commanders, were central to the defence of Kyiv. Co-ordination between the army, Territorial Defence, the police and several other armed units of Ukraine’s security services worked well, in a way which they had failed to do in 2014. Then the army had been run down by Viktor Yanukovych, a Moscow loyalist who served as Ukraine’s president from 2010 until he was ousted in 2014. The security services were riddled with pro-Russians who have since been purged.

Look at the map and it is easy to understand the Russian plan for Kyiv. The mighty Dnieper River runs through the capital. North of the city it is kilometres wide and runs all the way up to the border with Belarus. The Russians came for Kyiv in a pincer movement advancing south. But on both banks they were quickly stymied.

On March 10 their advance on the left or east bank was stopped in the town of Skybyn when an armoured convoy was ambushed and forced to retreat. The Russians found themselves blocked on the right bank too. On February 24 they seized Hostomel airport using helicopters only to be driven out by the Ukrainians. The next day the Russians were back, but this time by road. They took the town of Hostomel, though fighting was intense, and then neighbouring Bucha. But then they failed to take Irpin, the next domino. Irpin falling would have brought them to the gates of Kyiv.

At this point Ukrainian ingenuity and Russian blundering brought the campaign to a halt.

The house of Dmytro Lysovyy’s parents lies 200m from the railway embankment near Hostomel. The Samsung executive had come there at the beginning of the war thinking he would be safer than in Kyiv.

On the second day of the invasion elderly friends of his parents, who did not have a smartphone, called to tell them where they had seen a Russian convoy close to the airport. Lysovyy immediately opened “STOP Russian War”, a Telegram chatbot created by the security services, and input the location. He also put a pin in the Google Maps location, screenshotted it and sent that, plus everything else he knew.

“I think many others made the same report,” he said.

About 30 minutes later the convoy was attacked by the Ukrainian military. In the distance the sky glowed orange from the flames, Lysovyy recalled.

Officials have since made it easier for citizens to upload enemy locations through the Diia app, a government portal for digital documents such as driving licences and Covid passes used by millions of Ukrainians.

Mstyslav Banik, a director at the ministry of digital transformation which created Diia, said that in the first days of the defence of Kyiv, before the Russians destroyed mobile masts to prevent Ukrainians disclosing their positions, their reports played “really a great role”, in defending the city.

Everyone was trying to help, he says, and this “is the new reality of war”.

People trapped behind Russian lines using chatbots, he said, were playing a 21st century version of partisans behind Nazi lines during the second world war. To make sure that the Russians do not feed Ukrainian positions into the chatbot, says Banik, somewhere in Ukraine teams filter reports before they are passed to the military.

Paranoid about what was happening, Russian troops went from house to house hunting for smartphones, according to Lysovyy and other witnesses in the newly liberated territories. They also destroyed laptops and any other device that could be used to communicate. A Kindle and a smashed phone still lie on the grass in front of his house.

Just as it was dangerous being a partisan behind the lines in the second world war, using a smartphone today can be equally deadly. In the village of Motyzhyn, 50km west of Kyiv, Hennadiy Merchynskyi was executed and dumped down a drainage shaft. Zoya Merchynskaya, his widow, reckoned he was murdered after the Russians found pictures of their tanks on his phone.

To cut off Ukrainians in the occupied territories Russian troops set about destroying 4G mobile transmission units. But that meant they could not use their own encrypted system. They also need 4G. This in turn made it harder for units following the original plan to communicate.

On the Dnieper 30km north-east of Hostomel lies the Kozarovychi dam, which controls the inflow of the smaller Irpin river. Soon after the war began the Russians attacked and damaged this dam. “It was a crucial mistake,” said Konoko — because the whole flood plain of the Irpin became inundated.

Blocked by Ukrainian resistance further south at Irpin, the Russians found it impossible to cut across eastward in significant numbers at Moschun and then turn south to attack and enter the capital. By blowing up the dam the land that lay between Hostomel and Moschun had returned to the impenetrable wetland it had been before it was built.

In normal times you can reach Kyiv through Horenka, another small town south of Moschun, but the damage here and the shattered warehouses and the massive crater at the Kuehne+Nagel warehouse testify to the ferocity of the failed Russian attack. As at Irpin the Russians were simply unable to break Ukrainian resistance.

The Russians had taken Moschun at the beginning of the war. But with their path to Kyiv blocked at Horenka, where the Ukrainians had also partially blown the bridge, now only a couple of small, single-track roads across the railway remained to reach the capital. These were vulnerable to attack.

So, said Konoko, the Russians tried to get across using pontoons but as the water rose it became impossible to get significant numbers of vehicles and men across fast enough. Konoko’s men attacked with anti-tank weapons or called in artillery strikes. They took back Moschun on March 26.

The Russians had, in effect, come down a funnel and been blocked, creating the widely reported traffic jam of military vehicles stretching along 65km of road to the north. Unable to move forward, bombarded by the Ukrainians, harried by their small mobile units and fast losing men and equipment, the Russians decided to cut their losses on March 31 and run.

Kyiv had been defended and so the first chapter in Russia’s latest onslaught on Ukraine ended. Now the war has moved to the east. But it is telling that the Ukrainians are not yet talking of victory in Kyiv.

On Friday, Brigadier-general Oleksandr Hruzevych, the army’s deputy chief of staff, said that if the Russians succeeded in taking Donbas they might attack the capital once again. “Yes, now there is a certain lull in Kyiv Oblast [district] but not for the military,” he said.