This book aims to elaborate the Mosul Question, which was dispute first between the Great Britain and the Ottoman Empire and later between the Great Britain and Turkey.It attempts to analyze the resolution process of the Mosul question as a result of a very complex process between the years 1918-1926, with various political, diplomatic,military and legal dimensions by taking the fact into consideration that the Great Britain was the strongest member of the League of Nations, but Turkey was not even a member. The resolution of the Mosul question is a cornerstone in the history of the Middle East. It is almost impossible to comprehend the sources of problems in Iraq and in the Middle East today without any information about the history of the Mosul issue. The first Iraq war in 1990-1991 and the Second Gulf War in 2003, once again confirmed that the rich sources of oil have made Iraq the center of clash of interests after decades. This book will help people who study various disciplines such as International Relations and History. Additionally, it will provide new directions to everyone who is interested in history and international politics.