This monograph examines the evolution of United States Army deployment operations through the failures during the 1898 Santiago Expedition's mobilization through Tampa, Florida. The failed experiences from the Spanish-American War provided the evolutional foundation for successful deployment operations to France during World War I. The results from the experiences in Tampa have developed in current United States Army doctrine Field Manual 3-35, Army Deployment and Redeployment. In 1898, the United States Army failed to plan for basing, tempo, and operational reach, three elements of operational art, now foundational in current doctrine. Implications from this expedition are relevant in today's contemporary operating environments as United States global commitments require efficient and effective deployment support to project and sustain American combat power. Planners must consider basing needs with expandable and retractable capabilities to support operations. Commanders must understand deployment tempo operations in today's aggressive environment consisting of enemy Anti-Access / Anti-Denial measures. Finally, basing must provide operational reach capabilities able to support coalition and multi-national force partners. By successfully incorporating these three elements of operational art into deployment operations today, the United States military is able to link tactical action in time, space, and purpose toward the attainment of strategic objectives. The American entrance into World War I created one of the greatest military logistics problems the United States had ever faced. Sustainment planners successfully marshalled millions of tons of supply and mobilized almost two million men, solving a complex organizational and resource management problem. The United States required the movement of troops and equipment from countless locations within the country to a central port of embarkation for follow-on movement to the war zone. New York City was the hub for overseas transit to France. The United States established the Embarkation Service in 1917 as the central organization to oversee all ports of departure from the United States as a result. The New York Port of Embarkation employed twenty five hundred officers working in various roles at piers, embarkation camps, and hospitals. New York Harbor and its subports deployed 1,798,000 soldiers by the war's end with a peak of fifty-one thousand troops sent overseas in one day, which exceeded all previous one-port records. In comparison to prior Army deployment operations, the ports of New York were a model of efficiency and control during World War I. Regulating throughput was paramount to sustaining a continuous flow of movement. The United States government established the War Industries Board in 1917 to prevent inefficient competition in the private transportation sector and to effectively synchronize and regulate movement throughout the system. This board centralized control of railroads by the United States government and alleviated inbound shipment congestion.