Insurgency and irregular war continue to be a prevalent phenomenon in the international system. Fighting irregular wars challenge military doctrine used by established militaries across the developed world. These militaries invariably end up combating insurgencies through train and equip missions, although the adoption of train and equip usually happens after the insurgency has become well established. This book examines and analyzes approaches taken by the organized militaries from Afghanistan, Turkey, and Columbia in fighting their insurgencies, and the role that the train-and-equip mission played in preparing their respective militaries for their mission. To support the research, each case study is built upon an analysis of the history of each insurgency and the counterinsurgency (COIN) response from the state and military forces. How did the countries train and equip their forces to battle the insurgency? What findings and policy implications can be derived from examining these different COIN case studies?This book finds that the training and equipping mission should be a top priority for all nations fighting an insurgency. In addition, the successes and failures from the three case studies examined show that regardless of the cause of theinsurgency, once the insurgency is in full swing, one of the key elements to defeat the insurgency is with a properly trained self-sustaining force.