British–Turkish relations were transformed in the first half of the 20th century, from a state of belligerence during the First World War, through a period of heated confrontation over the fate of Mosul and trade and business access to the new Republic of Turkey, to rapprochement and financial cooperation in the 1930s, and finally a formal military alliance under the auspices of the North Atlantic Treaty Organisation. The edited collection provides a selection of important chapters by senior and early-career scholars from Britain, Turkey, and the wider world. The chapters use new sources to address issues as diverse as the Turkey–Iraq frontier, colonial governance in Cyprus, the legal rights of foreigners in Istanbul, commercial relations through the era of the Great Depression, contested neutrality in the Second World War, and the search for new alliances in the Cold War. Knowledge of this tumultuous transition and its impact on public memory is key to understanding points of tension and cohesion in present-day UK-Turkey relations. The chapters in this book were originally published in the journals Middle Eastern Studies and the Journal of Balkan and Near Eastern Studies.