War amplifies and magnifies the violence that children normally experience every day.

Where there is a pejorative view of girls and boys, or where there is impunity and no rule of law, it simply becomes worse for children when war breaks out, Bissell said.

Education can help protect children in many conflicts. It gives children a sense of normality, but also can protect them from being recruited by armed groups.

Thomas Lubanga, who has been imprisoned by the International Criminal Court for using children to fight in his rebel group in Congo, recruited many of them in communities without a functioning school or health service, Bissell said.

"There's no silver bullet but for UNICEF education is a huge intervention which we know yields results," she added.

The education system itself is under attack in many countries. Schools and universities have been attacked by armed groups in at least 70 countries over the past five years.

"The attempted murder of Malala Yousafzai (in Pakistan), and the kidnapping of 276 Nigerian girls by Boko Haram (militants), has finally woken the world up to the struggle that children face from those who will kill to stop them receiving an education," the UNICEF report said.