Two-part series telling the story of Britain's war in Afghanistan starts by examining the buildup to the conflict, revealing a story of confused aims.

Eight years ago the British Army arrived in Helmand in Afghanistan confident they could keep the peace, defeat the Taliban and rebuild the impoverished province. Now Britain's troops are leaving - 453 have given their lives. This two-part series tells the story of the conflict in Afghanistan and asks what has been achieved and whether, after such a bruising experience, the British have the will to fight in distant lands again.

Part one examines the buildup to the conflict and reveals a story of misplaced hope and confused aims that quickly led to the very real threat of a catastrophic defeat.