War Plan Red

War Plan Red
War Plan Red was a U.S. strategic plan in the event of war with the British Empire. "Blue" indicated the United States while "Red" indicated the British Empire, whose territories were given their own different shades of red: Britain (Red), Newfoundland (Red), Canada (Crimson), India (Ruby), Australia (Scarlet), New Zealand (Garnet), and other areas shaded in pink which were not part of the plan. The Irish Free State, at the time independent within the British Empire, was named "Emerald" in green.
Date 1920s to 1930s Location North America, British West Indies and Asia-Pacific region Status Planned at lower levels; never considered by Congress or President; never carried out
Belligerents
United States  Philippines (as an Insular Government from 1901 to 1935 and a Commonwealth from 1935 to 1946)	British Empire  United Kingdom  Canada  Newfoundland  Australia  New Zealand  Irish Free State  India
Commanders and leaders
The President	King George V

War Plan Red, also known as the Atlantic Strategic War Plan, was one of the color-coded war plans created by the United States Department of War during the interwar period of 1919–1939, covering scenarios related to a hypothetical war with the British Empire (the "Red" forces, likely in reference to the Red Ensign). Many different war plans were prepared by mid-level officers primarily as training exercises in how to calculate the logistical and manpower requirements of fighting a war,^[1] and War Plan Red outlined those steps necessary to defend against any attempted invasion of the United States by British forces. It further discussed fighting a two-front war with both Japan and Great Britain simultaneously (as envisioned in War Plan Red-Orange).

War Plan Red was developed by the War Department after the 1927 Geneva Naval Conference, and approved in May 1930 by Secretary of War Patrick J. Hurley and Secretary of the Navy Charles Francis Adams III and updated in 1934–35. It was a routine hypothetical exercise that neither required nor received presidential or congressional approval.^[2]

With the outbreak of World War II in 1939, it was decided that no further preparations would be made but the plans were to be retained.^[3] War Plan Red was not declassified until 1974.

The war plan outlined actions that would be necessary if, for any reason, the US 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 an invasion of the United States. The assumption was taken that at first, the US would fight a defensive battle against invading British forces, but the US would eventually defeat the British by blockading Canada's ports and cutting off its food supplies. It is debated whether this would have been successful, however, and if the plan would have ultimately resulted in a stalemate.^[4]