They get abandoned. They run away too.
Children tend to get forgotten about in wars. There is an assumption that there are always adults to look after them. There is an idea that even if their father has died fighting their mother will be there for them - even that there will be extended family there to care for them.
It doesn't work that way. There will always be "unaccompanied" children. "Unaccompanied" is the term used for children who have no adult to take responsibility for them.
There was an article in the Guardian yesterday about taking such children into Europe. They should not be in refugee camps or wandering through Europe alone. I doubt anyone would think that was right. Most of them will be boys, many of them in their teens. Many of them will learn to be criminals - in order to survive. Some may become radicalised. It is the sort of thing that needs to be prevented at all cost.
They need to be educated. They also need to be employed. It's a massive problem but they will be a much bigger problem if the situation is not dealt with. The idea that we "just let them in" - to Australia and New Zealand and North America as well as Europe - is not the answer. We need to let them in on the basis that they will be required to attend school and further education and that they will gain skills their own countries can use. They need to be given shelter on the understanding that they will one day return home to help rebuild their own countries.
"When the war is over we will need the young people. The best young people have gone," someone told me. He is deeply concerned by the situation in his home country. There is no planning for the future. Everyone is too busy simply trying to survive right now.
Europe took in more than a million migrants last year. Not all of them were refugees. Many of them were people who saw an opportunity to leave their home country and seek a better life elsewhere. It is perfectly understandable but it is not sustainable.
Providing for refugees, those people who have nowhere to go and who genuinely fear persecution in their own countries, is a duty. They have a right to protection.
Providing for people who wish to migrate in search of a better life is something different. There is no right to migrate. We have to recognise the difference between refugees and migrants.
Simply stopping the fighting is not enough to stop a war. It takes years for wars to be over, sometimes generations. The children in the middle of it all are still the best hope for the future.
They need to be educated. They need to be given the skills their countries will need. They need to told that "one day you will go home and help to rebuild your country because your country needs you". Yes, it will be expensive. Yes, it requires resources we don't presently have but we must find. If we don't then the situation will become far worse.
It is time to start thinking about the future. We have left it too long.