For 40 years, the French government has been fighting a secret war in Africa, hidden not only from its people, but from the world. It has led the French to slaughter democrats, install dictator after dictator – and to fund and fuel the most vicious genocide since the Nazis. Today, this war is so violent that thousands are fleeing across the border from the Central African Republic into Darfur – seeking sanctuary in the world's most notorious killing fields

I first heard whispers of this war in March, when newspapers reported in passing that the French military was bombing the remote city of Birao, in the far north-east of the CAR. Why were French soldiers fighting there, thousands of miles from home? Why had they been intervening in Central Africa this way for so many decades? I could find no answers here – so I decided to travel there, into the belly of France's forgotten war.