War Plan Red

Joint Army and Navy Basic War Plan Red was one of the color-coded war plans created by the United States Army and Navy in the late 1920s and early 1930s to estimate the requirements for a hypothetical war with the United Kingdom (the "Red" forces). War Plan Red discussed the potential for fighting a war with Britain and its Empire and outlined those steps necessary to defend the Atlantic coast against any attempted mainland invasion of the United States. It further discussed fighting a two-front war with both Japan and Britain simultaneously (as envisioned in War Plan Red-Orange).

War Plan Red was developed by the United States Army following the 1927 Geneva Naval Conference and approved in May 1930 by Secretary of War Patrick J. Hurley and Secretary of Navy Charles Francis Adams III and updated in 1934–35; it was not presented for presidential or Congressional approval. Only the United States Congress has the power to declare war.

In 1939, on the outbreak of World War II and Britain's war against Nazi Germany, a decision was taken that no further planning was required but that the plan be retained. War Plan Red was not declassified until 1974.

The war plan outlined those actions that would be necessary if for any reason the U.S. and Britain went to war with each other. The plan assumed that the British would initially have the upper hand by virtue of the strength of the Royal Navy. The plan further assumed that Britain would probably use its base in Canada as a springboard from which to initiate a invasion of the United States. The assumption was taken that at first Britain would fight a defensive battle against invading American forces, but that the U.S. would eventually defeat the British by blockading Britain and cutting off its food supplies.

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