Unwinnable: Britain's war in Afghanistan, 2001-2014

British and US forces could have successfully withdrawn from Afghanistan in 2002, having done the job they set out to do: to defeat al-Qaeda and stop it from launching further terrorist attacks against the West.

Instead, British troops became part of a larger international effort to stabilise the country.

Yet over the following 13 years the British military paid a heavy price for their presence in Helmand province; and when Western troops departed from Afghanistan in 2014, they had failed to stop a Taliban resurgence.

In this magisterial study, Theo Farrell explains the origins and causes of the war, providing fascinating insight into the British government's reaction to 9/11 and the steps that led the British Army to Helmand.