United States color-coded war plans

During the 1920s and 1930s, the United States military Joint Army and Navy Board developed a number of color-coded war plans to outline potential U.S. strategies for a variety of hypothetical war scenarios. The plans, developed by the Joint Planning Committee (which later became the Joint Chiefs of Staff), were officially withdrawn in 1939 in favor of five Rainbow Plans developed to meet the threat of a two-ocean war against multiple enemies.

The use of colors for U.S. war planning originated from the desire for the Army and Navy to use the same symbols for their plans. At the end of 1904, the Joint Board adopted a system of colors, symbols, and abbreviated names to represent countries. Many war plans became known by the color of the country to which they were related, a convention that lasted through World War II. As the convention of using colors took root, some were eventually reused, such as Grey, which originally referred to Italy but eventually became a plan for the capture and occupation of the Azores.

In all the plans the U.S. referred to itself as "Blue".

The plan that received the most consideration was War Plan Orange, a series of contingency plans for fighting a war with Japan alone, outlined unofficially in 1919 and officially in 1924. Orange formed some of the basis for the actual campaign against Japan in World War II and included the huge economic blockade from mainland China and the plans for interning the Japanese-American population.

War Plan Red was a plan for war against Britain and Canada. British territories had war plans of different shades of red—the UK was "Red", Canada "Crimson", India "Ruby", Australia "Scarlet" and New Zealand "Garnet". Ireland, at the time a free state within the British Empire, was named "Emerald". The plan was kept updated as late as the 1930s and caused a stir in American–Canadian relations when declassified in 1974.

War Plan Black was a plan for war with Germany. The best-known version of Black was conceived as a contingency plan during World War I in case France fell and the Germans attempted to seize French possessions in the Caribbean or launch an attack on the eastern seaboard.

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