By the close of the 19th century, the United States was no longer a continental power, but had become a nation with interests that spanned the globe from the Caribbean to China. Consequently, the country faced a new set of strategic concerns, ranging from enforcing the Monroe Doctrine to defending the Philippines. As a result of the United States' new geostrategic environment, the armed services had to establish a system for the creation of war plans to defend the country's interests against possible foreign aggression. A Joint Army and Navy Board, established in 1903, ordered the creation of war plans to deal with real and potential threats to American security. Each major country was assigned a colour: Germany was Black, Great Britain Red, Japan Orange, Mexico Green and China Yellow. War plans were then devised in case Washington decided to use force against these or other powers. Based on plans and studies drawn from a variety of archival sources, this volume describes the origin and evolution of the various plans and places them within the context of the United States' foreign and military policies.