When do 'troubles', riots and insurgency become war? How does a liberal state respond to an internal war within its own borders? How does it define the rules of engagement for its armed forces? These questions, amongst others, faced the British government in 1969, when it decided to send the British Army to the streets of Northern Ireland.This is the first academic study of the British Army in Northern Ireland, featuring Scottish, Welsh, Irish and English regiments. It investigates the complex experiences of soldiers during the often-controversial Operation Banner (1969-2007). The experiences of these soldiers raise many important and difficult questions on war and policy. Featuring key interviews with former soldiers, paramilitaries and Special Branch detectives, amongst other key actors, the authors attempt to answer these questions and enhance our knowledge of conflict resolution by providing a deep analysis of one of the most significant British military operations since the Second World War.