On February 24, war returned to Europe at a scale not seen since 1945, since the establishment of the United Nations and since promises of protection were enshrined in the Geneva Conventions.
For all the lessons available in the pages of history, a new dark chapter is being written in Ukraine.
For all the effort to avoid a third world war, global leaders now fear it is one wrong move away.
And for all the work to develop humanitarian law, Ukrainian children are being killed in a war they're too young to fully understand.
Ukrainian President Volodymyr Zelenskyy is attempting to negotiate for peace, but the reality for many of his people is that they may not have homes to return to, that the damage has been done, that the trauma has been inflicted.
Not since World War II has the world seen a refugee crisis at the scale and speed of what is happening in Ukraine.
A quarter of the population have been forced from their homes.
In the space of five weeks, 4 million people have left the country.
One in two Ukrainian children have now lost the security of a stable home.
One in two.
In the western city of Lviv, Ukrainians funnel out of their country. The crowds have been immense, the needs great and the local response exceptional.
It's on the upper level of the railway station where some of the most harrowing stories can be heard.
In a room warmed and lined with mattresses, mothers and their young children try to rest.
Perhaps they will have to wait a day for a place on a train out of town. Perhaps they've already been travelling for four.
This room fills and empties as the trains from the east arrive and those going west depart.
UNICEF representative on the ground in western Ukraine James Elder said the scale of stress on the children of Ukraine was "mind-boggling".
"By and large, the vast majority of children in Ukraine, just over four weeks ago were going to school, playing football, playing with friends, going to dance, seeing their grandparents," he said.
"A month later, one in two of those have been ripped out of their homes because of war."
James explains that when the Syrian war started 11 years ago, it took 2.5 years for 1 million children to become refugees.
There have been reports of children going missing and grave fears for their safety as UNICEF warns the risk they will be trafficked across Europe is real and immediate.
There are documented instances of children travelling across Ukraine on their own.
Even for those who escaped early in the invasion — who may not have seen violence themselves — the upheaval is likely to cause an immense amount of stress.
And then there is 10-year-old Dima, who knows his friend has died and doesn't understand why Ukraine and Russia can't "be friends".
"There was a classmate who lived on a Romanska street in a house and a rocket flew into their house and exploded," he said.
"Horrible things are happening."
Dima and his mother Julia are from Sumy — a Ukrainian city hit hard by Russian air strikes.
"I know a family. They had three children, dad, mum and they all died," Julia said.
"Many houses were bombed, maybe 20. A lot people died. Some people were our [friends]. They are ruined. On the ground."
Julia and her two boys escaped via a humanitarian corridor that opened in the third week of the war and are now sitting on the floor of the mothers' room.
They've travelled for two days and plan to cross into Hungary.
"It was really difficult to escape," Julia said.
"There is no other possibility to leave the town, only using this green corridor because when you leave by your car in the territory that is very dangerous, all the [people in] cars, even with women and their children, [they were] killed by guns.
"With children and the bags, it was really exhausting. For 48 hours you look after your kids, take your bags with you, move all the time, no sleep, no rest, all the time sitting on the ground, on your bag without any comfort."
The mothers' room is a place for women and children up to the age of eight.
People come and go all night. There is a makeshift medical centre in an adjoining room where children are given urgent care, food is passed out and every now and then someone walks in with a megaphone, breaks the silence and announces available seats on a train to Poland.
Despite the desperation, there's no rush. Everyone is willing to wait their turn.
For a room full of children, it's remarkably quiet.
James explains that even from early in the invasion, UNICEF staff have seen early signs of trauma among the children at the Ukraine-Poland border.
"Mothers would talk about their babies not crying — that's the onset of trauma. Mothers would talk about their children just sleeping all the time — that's the onset of trauma," he said.
"Mothers would talk about their children not eating — same thing.
"It was just this gut-wrenching journey — the last stages of a journey — and these, we are meant to believe, are the lucky ones escaping war."
The lessons of history
This part of the world has a long history of occupation, war and fighting for independence.
Early in the 20th century, the city of Lviv was part of the Austro-Hungarian empire, and then part of Poland after World War I. The city was seized by Soviet soldiers in 1939 and was then invaded by Nazi Germany during World War II.
At the downfall of the Soviet Empire in 1991, Lviv became part of an independent Ukraine and is considered to have deep nationalistic and patriotic roots.
Some Lvivians believe the cultural and social significance of their city makes it a target, and just last week, a Russian missile strike breached the city limits.
At the moment, the city is still a safe haven.
Elderly people here who were children in World War II are reeling from the reality of a new war.
Svetlana Vasiliyevna, 85, is originally from the Donetsk region, but was living in Irpin when Russia invaded Ukraine in February.
She is sitting outside the Lviv railway station, seething as she describes how she has been treated, distraught at being displaced again.
She brings up World War II and how she was taken from her parents as a child and forced into labour in Germany.
"First we lived in a camp," she said.
"They took me to work in a kitchen ... and my mother fell to her knees, [saying] 'Take me, take me.'
"There was a huge canteen for Germans. Before eating, they were all shouting 'Heil Hitler'. This is what I remember."
It's estimated 20 million "foreign civilian workers, concentration camp prisoners and prisoners of war from all of the occupied countries" were forced into labour by Nazi Germany during World War II.
At the height of the so-called "Ausländereinsatz" — the use of foreigners — in August 1944, 6 million civilians were performing forced labour in the German Reich, most of them from Poland and the Soviet Union, according to the German Forced Labour Archive.
Eighty years later, Svetlana is trying to reach Germany; this time to live with her son. And this time fleeing aggression from the east.
There is a cruel symmetry to her experience — the bookends of her life.
"We'll see how it goes because now it's already two days without sleep and without food," she said.
"[My daughter] is standing somewhere in line in there. How it will work out? There are no words."
By 1945, after six years of worldwide war and the horrors of the Holocaust, hundreds of thousands of children were missing and millions were homeless.
What happens to the families torn apart and the children displaced in the current war depends very much on what happens next, according to historian and director of the Lviv Regional Universal Scientific Library Ivan Svarnyk.
He believes as long as Lviv is secure, it will continue to shelter those who don't want to leave Ukraine.
And for the women and children who leave, there is strong reason to eventually come home.
"I am convinced about this, especially because [it's] mostly women and children who leave and men stay either to fight or to work on defence. And that means the family is separated and it will then reunite," Ivan said.
As he talks about World War II and the Soviet occupation of Lviv, Ivan points out the bags of Molotov cocktail supplies and crates of vehicle traps at the entrance to the library.
Determined not to let the documentation of the region's history be destroyed by its current war, this former member of the 1950s anti-Soviet resistance movement is ready to defend the shelves of books that hold the lessons of the past.
And he implores current world leaders to heed them.
"Unfortunately, humanity has turned out to be a community that learns almost nothing from its mistakes," Ivan said.
"Everything depends on whether there will be enough smart people to understand [their] responsibility to the next generations.
"We're fighting for the life of our people. There is no other way."
Credits:
Reporting and additional photography: Emily Clark
Photography: Brendan Esposito
Research: Agnieszka Suszko
