This study presents a detailed narrative and analysis of one of the aspects of aerial warfare which the United States Air Service performed during World War I–observation aviation. While bombardment and pursuit aviation of the American Expeditionary Forces caught the public fancy and subsequently have received substantial amplification by air power enthusiasts, it was the use of airplanes for liaison purposes and for close-support observation and reconnaissance that was the most significant in terms of achievement. This book is part of the World War One Centenary series; creating, collating and reprinting new and old works of poetry, fiction, autobiography and analysis. The series forms a commemorative tribute to mark the passing of one of the world’s bloodiest wars, offering new perspectives on this tragic yet fascinating period of human history. Each publication also includes brand new introductory essays and a timeline to help the reader place the work in its historical context.