When wars break out, international attention and media reporting invariably focus on the most immediate images of human suffering. Yet behind these images is a hidden crisis.
In conflict-affected, poor countries, 28 million children of school age are unable to attend school - almost half of the world total.
Across many of the world's poorest countries, armed conflict is destroying not just school infrastructure, but the hopes and ambitions of generations of children.
Today, in London and other cities worldwide, UNESCO launches its 2011 Education For All Global Monitoring Report, focussing on the hidden crisis of the effects of armed conflict on education.
While education systems have the potential to act as a powerful force for peace, reconciliation and conflict prevention, they also have the potential to reinforce intolerance and inequalities.
Education can become highly-politicised in conflict-affected countries. In addition, the lack of education, and the resulting economic hopelessness, felt by many young people in conflict-affected areas has also made them easy prey for recruitment by armed militias.
When armed conflict ends and governments start to reconstruct education systems, they need to assess the post-conflict environment carefully.
They have to consider how policy choices will be perceived in the light of long-standing rivalries and partially-resolved disputes.
That means addressing issues such as education governance, language of instruction, and teaching of subjects like religion and history.
In some situations, aid effectiveness has been compromised by the national security agendas of major donors.
Development assistance to conflict-affected states is heavily skewed towards countries viewed as strategic priorities - notably Afghanistan, Iraq and Pakistan.
The international aid system needs to be more proactive in addressing education needs in conflict-affected countries, both by matching the aspirations of communities at a local level and providing funding on a consistent and guaranteed basis to develop good education systems at a national level.
For this to happen, the financial contribution of the international community needs to be significantly increased; currently education accounts for just 2% of humanitarian aid.
Today's report dramatically highlights that, if even a tiny fraction of the money spent on the military was redistributed to education, millions of children across the developing world would have a better chance in life. In 2006, the UN Secretary General established a new UN Peace Building Commission, with a peace-building fund of $360m.
While the reform of security and justice, political and economic systems features prominently, there are lessons to be learned from contexts such as Bosnia and Northern Ireland.
In both cases, even more than a decade after peace agreements, education reforms are highly-politicised and contentious.
This suggests that it is crucial to engage in social policy areas, such as education, at an early stage as part of peace-building processes.
What today's report highlights is that no country can hope to establish lasting foundations for peace unless it finds ways of building mutual trust between citizens, and between citizens and government.
And the place to start is in the classroom.