War Plan Red: A 1930s Plan For a US Invasion of Canada & War With The British Empire

Map created by OwenBlackerThe map above shows the US War Plan Red:

Also known as the Atlantic Strategic War Plan, was a plan for the United States to make war with the British Empire (the “Red” forces).

It was developed by the United States Army following the 1927 Geneva Naval Conference; and approved in May 1930 by the Secretary of War and the Secretary of Navy and updated in 1934–35.

In 1939 it was decided that further planning was no longer applicable but that the plan be retained.

• Canada (Crimson),
• United Kingdom, and Newfoundland (Red),
• British Raj (Ruby),
• Australia (Scarlet),
• New Zealand (Garnet),
• Ireland — by that time no longer part of the British Empire (Emerald),
• and other parts of the British Empire (pink — not part of the plan),
• United States (Blue).

War Plan Red was a theoretical war plan developed by the United States military in the early 20th century.

It outlined strategies for a potential war with the British Empire and was part of a broader series of U.S. military plans that addressed conflicts with various nations (color-coded for identification).

Here’s a summary of War Plan Red and related components:

War Plan Red (Main Plan)

• Focus: A war between the U.S. and the British Empire, particularly focused on Canada as a staging ground.
• Main Targets:
  • Canada (“Crimson”): Recognized as the critical first theater due to its proximity to the U.S. and its strategic importance to Britain.
  • United Kingdom (“Red”): Direct confrontation with Britain was deemed logistically difficult due to the Atlantic Ocean.
  • Newfoundland: Was considered a possible staging area for British forces in the Atlantic.
• Military Actions:
  • U.S. forces planned to invade and occupy key Canadian territories to deny their use to Britain.
  • Focus on capturing Halifax (a major Canadian naval base) and major transportation hubs (e.g., Montreal and Toronto).
  • Blockade British territories and maritime routes.
• Naval Strategy: Prioritize the destruction of British fleets and trade routes, especially in the North Atlantic.

Crimson Plan (Canada’s Role)

• Canada’s Role: Canada (Crimson) was crucial to the plan because it served as Britain’s largest and closest dominion. U.S. planners anticipated that capturing Canada would severely disrupt British military logistics and morale.
• Expected Canadian Defense: Canada’s military was relatively small at the time, but the U.S. expected it to resist and delay U.S. advances until British reinforcements could arrive.

British Counterplans (Defense of Canada)

• While there is limited specific documentation on detailed British counterplans to War Plan Red, the general British strategy revolved around the following:
  • Naval Dominance: Relying on the Royal Navy to control the Atlantic and prevent U.S. reinforcements from reaching Canada or attacking other British territories.
  • Canadian Defense: Strengthening Canadian militia and defensive positions along the U.S.-Canada border to delay any invasion and even possible pre-emptive attack (see: Defense Scheme No. 1).
  • Strategic Staging Areas: Using Newfoundland and other North Atlantic territories as forward bases for counteroffensives.
  • Empire Coordination: Leveraging dominions like Australia, New Zealand, and India for manpower and resources.

Other Dominion Roles:

• Australia (“Scarlet”) & New Zealand (“Garnet”): Would likely contribute naval and ground forces in the Pacific and Indian Oceans to counter U.S. naval dominance.
• British Raj (“Ruby”): A massive reserve of manpower for the British war effort, though not directly implicated in War Plan Red due to its distance.
• Ireland (“Emerald”): By the 1930s, Ireland was no longer part of the British Empire. It would likely remain neutral, though its proximity to Britain made it strategically significant.

U.S. Naval Strategy

• The U.S. Navy planned to establish dominance in the Atlantic, isolating Britain from its empire.
• Key focus areas included:
  • Destroying British shipping routes.
  • Severing communication lines between Britain and Canada.
  • Protecting U.S. coasts and ports from British counterattacks.

Plan Evolution and Abandonment

• War Plan Red and related plans were never acted upon and were primarily theoretical exercises.
• By 1939, with World War II looming, the U.S. shifted its focus from hypothetical conflicts with Britain to planning against Axis powers.