In the fall of 1996, the Department of the Air Force published its vision for the twenty-first century Air Force. The vision, entitled Global Engagement, presented a new strategy to guide the Air Force in meeting the many challenges of the first quarter of the twenty-first century. It is a vision of air and space power and covers all aspects of our Air Force-people, capabilities, and support structures. Global Engagement is the first step in the Air Force’s back-to-the-present approach to long-range planning. As the Air Force charts its course into the twenty-first century, valuable insight is gained by examining the beginnings of that course-the initial vector that has steered air power from its birth at the beginning of this century and will now carry air and space power into the next. The United States Air Force is inseparably linked to many aviation pioneers and air power advocates. The wisdom and vision of these early airmen have steered the development of air power throughout this century. Among those early visionaries, Brig. Gen. William Billy Mitchell was perhaps the most outspoken advocate of air power and an independent air force. Mitchell was not only a pioneer in military aviation, but an air power visionary. He was among the earliest to realize the value of air power and to see not only the profound changes it brought to his times, but its vast potential for the future. His wisdom is as fresh and relevant today as it was at the beginning of the century when he offered it. This collection of Mitchell’s thoughts on air power offered here should illuminate the vision offered by Global Engagement. Even though Mitchell set forth his thoughts nearly 80 years ago, the lineage can be seen between his vision and those principles that have guided our Air Force in the past, that guide our Air Force today, and that will guide the Air Force vision for the next century. Robert M. Hylton Colonel, USAF Commander, College of Aerospace Doctrine, Research, and Education