Historians have portrayed aviation in the First World War as a romantic alternative to the mass slaughter playing out on the ground and at sea. Young men volunteered for service in the air to escape the horrors of the trenches and their exploits made them into heroes a war-weary public could revere. As valuable as this diversion proved to civilian morale, it contributed little, if anything, to the military victory. Another global conflict broke out before aviation's destructive power matured into a potential war winning force. This characterization has allowed historians to discuss World War I without any meaningful analysis of what role aviation played in the fighting. Connections between the air war and ground and naval operations are missing from most contemporary accounts of the war. This dissertation argues that airmen contributed greatly, shaping the manner in which armies and navies functioned in ways that influenced the outcome of battles and the length of the war. Reconnaissance, observation and photography made up the branch of World War I military and naval aeronautics that most significantly impacted the fighting. Observation balloons and airplanes regulated artillery fire, infantry liaison aircraft kept track of the advances made by attacking troops and the retreats of defenders, aerial photographers produced pictures that aided operational planners and provided the basis for perpetually updated maps, and naval airplanes, airships, and tethered balloons acted as aerial sentinels in a complex anti-submarine warfare organization that developed in the last half of the war. In the decade following the armistice, aviation leaders had to abandon the proven aerial reconnaissance model they developed during the war in favor of organizations that specialized in bombing and aerial combat. Achieving independence from the army and navy, as well as simple financial survival in an era of draconian military budget cuts, forced them to demonstrate that airmen possessed their own ability to destroy the enemy. Acting as auxiliaries to the other services would no longer suffice. Aviators had to substitute for soldiers and sailors, not merely service them. This atmosphere prompted air power advocates like William Mitchell, Hugh Trenchard, and Guilio Douhet to preach the future potential of bombing and to minimize the past accomplishments of reconnaissance. The record compiled by the Second World War's bombing forces appeared to prove their arguments. This dissertation contends that in the aftermath of World War II historians examining aviation in the First World War joined their chorus. Instead of acknowledging the solid contributions made by aerial reconnaissance crews they have focused their analyses on the largely ineffectual record compiled by World War I bombing crews or the glamorous lives of the flying aces. Failing to uncover the type of massive damage produced by the U.S. Army Air Force, Britain's Royal Air Force, or Germany's Luftwaffe, they have dismissed the efforts of World War I aircrews as meaningless. This dissertation's goal is to give the First World War's aviators their rightful place in the war by documenting the achievements of reconnaissance airmen.