What you need to know:
- Women and children are still pouring out of a land being pummelled by what one called Russia's "creatures from Hell"
- Starting life over without the usual health and financial support systems, often without family members, in a new and unfamiliar country is not easy at an advanced age, Derbyshire said.
A heartbreaking human drama is playing out along Ukraine's borders -- fleeing refugees pass the homesick going back, while others who left and then returned flee for their lives for a second time.
Women and children are still pouring out of a land being pummelled by what one called Russia's "creatures from Hell".
But hundreds of thousands of refugees are returning home, determined to stay.
Many others have had to flee for a second time, having thought it was safe to go back only to find it was not.
An AFP team has been travelling along the country's frontiers to report the aftermath of the biggest exodus in Europe since World War II -- more than five million people according to the UN.
They met Iryna Ustyanska carrying her suitcases across a bridge into Sighetu Marmatiei in Romania.
She and her two children were refugees for the second time in a month, having fled from Odessa to Bucharest after the invasion as Russia bombings drew close.
They decided to return home at the beginning of this month but were only back a few hours before Russian air strikes shook the strategic Black Sea port.
"We thought the fighting was not so intense but we were wrong," she said, showing pictures on her phone of the black pall of smoke over the city.
Her daughter Olena, eight, and 15-year-old son Danylo had to say goodbye to their father for a second time, not knowing when they would see him again.
"It's very difficult for them," said Ustyanska.
"They hope we will be back very, very soon because they can't imagine living abroad without their father."
Theirs is a story typical of the tides of despair and hope pushing and pulling the waves of refugees.
Yet despite the dangers of a war entering what could be an even bloodier second phase, hundreds of thousands have decided to return to Ukraine and stick it out.
To try to tell all these stories, the AFP team drove 2,500 kilometres (1,555 miles) along the length of Ukraine's western frontier earlier this month, from the northernmost crossing in Dorohusk, Poland, hard by Belarus, to Isaccea in Romania in the south on the banks of the Danube.
'The quiet is scarier'
In the drizzle at Vysne Nemecke, a drab Slovakian border crossroads now overrun by lorries and tents, Tetyana Dzymik talked to anyone who would listen.
The 38-year-old art teacher fled her village near Bucha, a quiet commuter town near Kyiv now notorious after Russian troops were accused of massacring civilians there.
"Who does these kind of things? Not humans, only creatures from Hell," she said through her tears.
Distraught, the words tumbling from her lips, she told how Russian soldiers ransacked homes in her village, smashing windows and doors and defecating in bedrooms and sitting rooms.
Even though the Russians left in early April, Dzymik decided to leave to protect her baby son Olexiy and her 11-year-old twins, Danylo and Ivan.
"The quiet is scarier than the sound of explosions," said, clearly traumatised.
"When everything is exploding you understand something is going on. When everything is quiet, you don't know where these abominable people are."
Further south in Hungary, just beyond the Zahony railway crossing, Olesya Demechenko, 41, had finally reached safety and was having a bite to eat at the World Central Kitchen, a charity founded by Spanish-American celebrity chef Jose Andres.
She had come from Molochansk in the south. There, she said, the Russians chased the inhabitants away and pillaged their homes to make way for feared Chechen pro-Russian fighters, who are also deployed in Mariupol, 200 kilometres to the east.
With her young son and some friends, Demechenko aimed to meet up with her husband, who works in a factory in Budapest.
Hungary has not been a welcoming place for migrants in recent years. During the 2015 migrant crisis, barbed wire fences sprang up to stop Iraqis, Syrians and Afghans from entering the country.
Viktor Orban, the country's recently re-elected nationalist leader, is considered Vladimir Putin's closest ally in the European Union.
"We may not be jumping with joy that Orban is leaning towards the Russians," Demechenko said. "But for us what matters most is to be safe."
Apart from Poland, where many of the nearly three million refugees it welcomed have decided to stay for now, most just transit the countries bordering Ukraine.
Their final destinations vary -- from Italy in the south to Estonia in the north. Often they choose somewhere they have friends or family.
'We love these people'
No two border crossings are the same.
In the Polish town of Medyka, a long line of humanitarian aid tents looks like a flea market at first glance. But here everything is for free.
Jehovah's Witnesses -- who are omnipresent along the border -- have set up opposite a Sikh food truck, while Israeli organisations rub shoulders with Egyptian Red Crescent workers.
A dozen kilometres to the west at the bustling Przemysl train station, a jovial French Catholic missionary from Calcutta, Brother Francois, is handing out meals and blankets and providing information to exhausted and disoriented refugees.
"They've been uprooted, they have no idea what their future holds but they still have their dignity and that's extraordinary," he said.
In his spare moments, Brother Francois plays Bengali music on his flute, to "bring a little joy" to people weighed down with sadness.
A little ways away, a volunteer Polish vet is waiting to vaccinate dogs and cats arriving on the next train.
Many Ukrainians flee with their pets, a comfort when everything else in their lives is turned upside down.
"More than ever they're part of the family," said Katarzyna Grochowska, who travelled 400 kilometres (250 miles) to help out at her own cost.
A town of 60,000 people that has seen up to 55,000 refugees arrive daily, Przemysl is "the world capital of volunteering", its mayor Wojciech Bakun said proudly.
"Police officers helping at the train station or in town stay on after their shift," he said.
Some have even taken families "home to their place for the night."
In Kroscienko, a bucolic valley in southern Poland, all was calm when AFP turned up.
Police officers were warming themselves around a wood fire when a young Ukrainian woman arrived with a baby strapped to her chest and two other children in tow.
Having crossed the border, she looked up at the sky, closed her eyes, and a tear rolled silently down her cheek. Relief, fatigue, sadness -- a storm of emotions were written on her face.
The officers rushed to help with her bags.
"We have not had a single problem with the refugees," the police chief said. "We love these people and they love us."
The contrast is striking with the situation in the north, along the Poland-Belarus border.
Journalists and humanitarian organisations are not welcome there where Polish authorities have built a wall to stop migrants, most from the Middle East, whom Minsk encouraged to try to cross there in the summer of 2021 during a stand-off with Europe.
All along the Ukrainian border, the flow of refugees has slowed in the past few weeks.
Since Ukraine doesn't allow men between the ages of 18 and 60 -- those of fighting age -- to leave, some 90 percent of refugees are women and children.
While they have escaped the fighting, other dangers lurk.
Women "are particularly vulnerable when it comes to sexual and gender-based violence because they are young and have kids," Moldova's UN Women representative Dominika Stojanoska to AFP.
They are also at risk from trafficking, she said, a warning echoed by the International Organization for Migration (IOM).
Children, especially those fleeing without their parents, are easy prey.
In the Polish town of Korczowa near the Ukrainian border, a shopping mall that has gone out of business has been converted into a refugee reception centre, with beds lined up in rows, and the sound of children playing echoing in the distance.
Libraries Without Borders (LWB) have set up shop in an empty store, with Ukrainian children laughing and chatting as they read books and play board and video games.
Their drawings of hearts, flowers and butterflies hang on the walls. The many pictures they draw of Ukrainian tanks firing at Russian tanks, or of Russian flags with big crosses through them were not displayed.
"We have children who arrive with signs of post-traumatic stress, and we steer them toward activities that will distract them from the life they have been living for weeks," said Clemence Loupandine of LWB.
Back in Hungary at the Zahony train station, two Britons in zany outfits hand toys donated by British children to kids stepping off the trains from Ukraine.
"It makes the parents see their children smile again," said Briton David Fricker, 39, a train driver who took unpaid leave to come to help out.
The two friends have lost count of the number of times it has made them cry too.
Going back again
More than a million people are estimated to have returned to Ukraine after fleeing, either because the fighting has moved away from their homes or because they just can't stand being away.
Appearing out of nowhere on a sunny day, a smiling Kateryna Bolotova turned up at the small Moldovan border post in Palanca.
In one hand she held her two dogs on leads and in the other a suitcase with a Ukrainian flag sticking out the top.
After five weeks in Germany, she was returning to her hometown of Odessa, an hour away by car.
"I miss my husband, my country... (Ukraine) was a very beautiful country, with very beautiful people," said the energetic 36-year-old lawyer.
In Germany "everybody has been very generous to me but I couldn't stay. I need to be here.
"Before the war, I travelled every month. I've been to 25 countries, but this trip from Germany back to my Ukraine was the best," she declared.
If she ever has to flee Odessa again, she won't leave Ukraine, Bolotova insisted.
"I think I can find a safe place in my country. I think that this (Russian) army cannot destroy everything."
Behind her, Tetyana Ponomareva, a 41-year-old port employee and her 19-year-old daughter Kseniia are queuing up in their car, a Ukrainian flag on the windscreen.
After fleeing to the Moldovan capital of Chisinau, they said they cried every day reading the news from home.
"Of course we are afraid, but for a month we've been crying -- we miss our parents, we miss our friends, we miss our home. We want to see them," Ponomareva said.
"Every day we've wanted to go, and today we simply decided to take the car and do it."
In Zahony, Volodymyr, a strapping 30-year-old nearly two metres (over six feet) tall, is returning to fight if they will take him.
The trained pilot got stuck in Georgia with his parents on holiday when the war began. All three were now waiting for a train to return to Kyiv, where Russia has recently loosened its hold.
"At the moment they are not taking pilots" for the Ukrainian air force, he said, because "we don't have enough aeroplanes".
Stuck at the border
Between those who leave with heavy hearts and those returning with renewed hope and determination, there are others marooned at the border, whose lives are on hold.
Briton Anthony Phillips wanted to fight for Ukraine's "foreign legion".
But the 30-year-old Londoner, who had a difficult childhood, was turned away.
Now he is now working for a charity at the Dorohusk Polish border crossing.
"I've been an orphan since the age of six. What touched me the most was stories about children leaving Ukraine with no parents, no clothes, nothing. It felt like me again..."
In Chisinau in Moldova, Viktoria Logvynova, a sprightly Ukrainian woman in her 80s, is stuck in a refugee reception centre.
"I didn't want to leave Kharkiv, my daughter made me," said the former music teacher.
Ukraine's second city is taking the brunt of the new Russian offensive.
"Even if the city is dying, I want to die with it," Logvynova said from her wheelchair.
A quarter of Ukraine's population is over 60, according to Justin Derbyshire, of the charity HelpAge, who warned of "the devastating impact" it was having on them.
This is "the 'oldest' humanitarian crisis in the world," he said.
Starting life over without the usual health and financial support systems, often without family members, in a new and unfamiliar country is not easy at an advanced age, Derbyshire said.
Meanwhile, a ferry was shuttling passengers across the Danube to Isaccea in Romania and back, a fitting symbol of the to-and-fro across Ukraine's border.
From the Romanian side of the river, Jaroslov Marukno, a 16-year-old from the industrial town of Dnipro in southern Ukraine -- now in Russia's sights -- looks on.
When did he think he will be able to make the crossing?
"In one month," he replied. "We have faith in the Ukrainian military."