Following the entry of the United States into World War I in the spring of 1917, the aviation units in the Signal Corps explored the possibilities of employing aircraft for military transport. Although the 1916 Pershing Expedition into Mexico occasionally had used airplanes for reconnaissance and to carry mail and dispatches, the equipment available during that operation proved unreliable. In 1918, the Signal Corps supplied airplanes and pilots to inaugurate the first U.S. airmail service, an operation expected to help train pilots and boost airplane production. This experiment did little for either goal, and the Post Office Department soon took complete control. Overseas, aircraft based in France sometimes carried a single officer or courier, or perhaps priority military dispatches, but the available single-engine, two-place airplanes permitted little else.

An effort to assist a force of 500 U.S. soldiers surrounded by the Germans during the Argonne Forest campaign in October 1918 achieved very little. Remembered as the “Lost Battalion,” the American unit recovered almost none of the supplies that U.S. airplanes dropped near its position. However, the beleaguered troops surmised the need to mark their location for better identification from the air, and the panels they laid out provided needed information to pinpoint their position and allow relief forces to fight through to them. The object lesson of aerial marking became standard procedure.

Before the end of the war, Brig. Gen. William Mitchell had begun plans for a massive aerial offensive against Germany that would rely on Allied use of extensive bombing as well as tactical air strikes. Mitchell’s planned aerial assault, moreover, included dramatic use of airborne forces. He proposed an airdrop of an entire U.S. infantry division behind the German lines, using Handley-Page bombers from the British Royal Air Force (RAF), followed by subsequent air cargo missions by the bombers to support these airborne units with ammunition and other supplies.  The U.S. high command had this remarkable gambit under serious consideration when World War I ended abruptly in November 1918. Mitchell’s concept clearly anticipated tactics used some twenty-two years later in the Second World War.

Hampered by parsimonious budgets and deteriorating equipment in the postwar era, planners had little opportunity to implement comprehensive plans like Mitchell’s. There were some bright spots, such as the Model Airways system, which operated from 1922 to 1926. Sponsored by several forward-thinking officers in the new Air Service, the Model Airways linked Bolling Field in Washington, D.C., with a number of military air-fields scattered across several midwestern states, down to Kelly and Brooks Fields in Texas. During the few years of its existence, the Air Service evolved a regularly scheduled mail and cargo service, as well as ad hoc operations. Equipment varied: available airplanes designated as cargo types were used and an occasional bomber was pressed into service. During its four-year history, the Model Airways completed several hundred flights and moved over sixty thousand pounds of cargo and more than 650 passengers. Federal legislation for commercial airmail service in 1925, coupled with specific restrictions on competing services under the Air Corps Act of 1926, put an end to the Model Airways. Its legacy of operational and logistical planning experience, however, proved to be a useful one. 

Miscellaneous air cargo activities took place during the 1920s and 1930s and the U.S. Army conducted limited exercises using parachutists, but doctrinal emphasis on bombardment and on aerial combat meant that comparatively less attention was expended on airlift concepts. Nonetheless, maneuvers during the late 1920s and early 1930s kept the idea alive and under discussion at the Air Corps Tactical School. The drawbacks of this limited approach became all too clear when the U.S. Army attempted to provide the nation’s airmail service during the late winter of 1934.

Domestic commercial air service, meanwhile, had made impressive progress by the mid-1930s. Private companies became skilled at developing airmail routes supported by requisite scheduling and logistical support. Passenger flying evolved during the early 1930s, along with improved aircraft and navigational equipment. Although not able to fly in every kind of weather or night conditions, the commercial airlines offered a valuable transportation service for that era. Early in 1934, questions about the legality of certain airmail contracts prompted federal action to cancel all of the current contracts and to rely on the Air Corps to fly the mail. The Air Corps confidently responded, on the basis of its earlier experience with cargo, maneuvers, and long-range navigation exercises for its bomber squadron—all of which, however, had taken place in favorable weather. Flying conditions during the early months of 1934 were actually abominable; a flurry of sixty-six crashes killed twelve Air Corps pilots trying to fly the mail. In the aftermath, improved training, weather forecasting, and navigational technology for transport duties were developed. 

Despite the embarrassing airmail venture, officers interested in aviation remembered earlier events that argued for a modern airlift capability. Among them was an emergency airlift mounted in 1916 to support a British garrison under siege by Turkish troops in Mesopotamia. A handful of single-engine RAF biplanes managed to drop several thousand pounds of supplies over a period of two weeks before Turkish forces defeated a relief column and the British surrendered. The RAF mounted a somewhat different sort of airlift during late 1928 and early 1929, when biplane transports successfully evacuated nearly six hundred people and twenty-four thousand pounds of belongings from Kabul, Afghanistan, during a period of tribal unrest. These operations dramatically illustrated airlift’s capabilities to transfer large numbers of personnel and cargo. Closer to home, from 1927 to 1929, U.S. Marines operating in Nicaragua used trimotor Fokker and Ford transports to carry troops, equipment, and dispatches. The Marines also used these aircraft for medical evacuation and to air-drop supplies to armed patrols deep in the Central American jungles. With this background and an awareness of airlift sharpened by the recent airmail experience, essential changes began to occur.

A reorganization of the Army Air Corps gave more authority to transport functions, including authorization for modern, twin-engine transport airplanes. In 1936, the Air Corps bought twenty new Douglas DC–2 transports, designating them C–33s and C–34s. The following year, the 10th Transport Group emerged as the first permanent logistics unit, replacing several provisional units that had come and gone over previous years. Additionally, General Headquarters Air Force (GHQ Air Force) built up its own tactical support. This sort of split in resources persisted as a source of contention for nearly a decade as various commands competed for air transport assets, especially in World War II. In any case, the total number of dedicated transport airplanes of useful capacity remained inadequate.  Against proposals for about 150 airplanes in the late 1930s, only 30 additional DC–2 types entered service through 1939. 

Moreover, the Air Corps had no large, four-engine transports for transoceanic missions. Compared with the record of commercial airlines, the inability of the U.S. military services to deploy intercontinental airlift was embarrassing. Following the first transatlantic flights of 1919, the development of commercial services required nearly two decades. Nonetheless, by the late 1930s, European countries like Britain, Holland, and France had pioneered impressive route systems throughout the continent, over the Mediterranean, and across the Middle East to various colonies in the Pacific region. The French and Germans operated airmail services across the South Atlantic between Africa and Brazil, on the South American coast. In the United States, federal support for Pan American Airways helped transform it into an intercontinental aerial system. By the late 1930s, Pan Am not only delivered mail and passengers throughout Latin America but also had inaugurated similar operations across the Pacific and Atlantic Oceans. 

Still, the majority of these efforts operated on a seasonal basis, required several days at a time, kept to a limited schedule of only one or two flights a week, and were beyond the means of all but the wealthiest travelers. Pan Am’s longest routes relied on big, four-engine flying boats built by Martin and Boeing. Another U.S. airline, Transcontinental and Western Air—later Trans World Airlines—(TWA), had introduced four-engine Boeing Stratoliner passenger transports on important domestic routes. Pressurized for high-altitude flights, they were in the forefront of modern airliner design.

Building on this legacy of U.S. airline experience and using commercial aircraft, the Army’s early, long-range airlift gained an invaluable ad-vantage. During the course of World War II, having built numerous weather stations and hundreds of airfields around the world in only a few years, the Army Air Forces commanded a large fleet of long-range transports that flew intercontinental schedules as a matter of course. That effort would provoke a postwar revolution in air transportation.