War Plan Red: The Forgotten U.S. Plot to Battle Britain

War Plan Red: The Forgotten U.S. Plot to Battle Britain

Darren - July 20, 2025

In the shadowy archives of U.S. military history lies a striking document: War Plan Red. Crafted in the 1920s and 1930s, this secret strategy outlined how the United States might engage in an all-out war with the British Empire. This plan was not mere fantasy; it was part of a broader era where nations meticulously prepared for worst-case scenarios, fueled by global uncertainty and fierce competition for power. The existence of War Plan Red highlights the intense atmosphere of suspicion and military planning that defined the early 20th century, a time when even America’s closest allies were viewed as potential rivals.

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1. The Origins of War Plan Red

War Plan Red: The Forgotten U.S. Plot to Battle Britain
Image Source: Wikimedia Commons.

The roots of War Plan Red can be traced to the uneasy aftermath of World War I. The United States, wary of shifting alliances and lingering imperial rivalries, began formulating detailed contingency plans against possible adversaries—including the British Empire. This practice reflected a broader strategic mindset: military planners believed that preparing for every conceivable conflict was essential to national security. The result was a series of color-coded war plans, with “Red” designating Britain as the hypothetical enemy (via U.S. Department of State).

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2. Why Britain Was Considered a Threat

War Plan Red: The Forgotten U.S. Plot to Battle Britain
Image Source: Wikimedia Commons.

Despite fighting side by side in World War I, the U.S. saw Britain as a potential rival due to its vast empire and dominant navy. The two nations competed for global influence, with tensions simmering over trade routes and colonial interests. This strategic rivalry was not unique; the U.S. military also developed War Plan Orange against Japan and other color-coded plans for different nations. These hypothetical scenarios reflected the era’s deep-seated anxieties and the belief that today’s ally could become tomorrow’s adversary (via HistoryNet).

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3. The Color-Coded War Plans

War Plan Red: The Forgotten U.S. Plot to Battle Britain
Image Source: Wikimedia Commons.

The U.S. military’s “color-coded” plans were a comprehensive approach to national defense. Each major potential adversary was assigned a color—Britain became Red, Japan was Orange, Germany was Black, and so on. War Plan Red was just one piece of this elaborate framework, reflecting the era’s obsession with preparedness for any threat. These plans were regularly updated and discussed at the highest military levels (via National Archives).

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4. The Canadian Front: A Key Battlefield

War Plan Red: The Forgotten U.S. Plot to Battle Britain
Image Source: Wikimedia Commons.

Because Canada was a loyal British Dominion, War Plan Red identified it as the primary theater of operations in any conflict with Britain. U.S. strategists envisioned rapid invasions targeting major Canadian cities like Montreal, Quebec, and Toronto, aiming to seize key railways and ports before British reinforcements could arrive. Multiple invasion routes were mapped out from the northern U.S. border, reflecting both geographic realities and the urgency of overwhelming Canadian defenses—an approach reminiscent of invasion plans against Mexico and Japan in other war scenarios (via CBC).

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5. Plans for Sabotage and Infrastructure Attacks

War Plan Red: The Forgotten U.S. Plot to Battle Britain
Image Source: Wikimedia Commons.

War Plan Red included detailed schemes to cripple Canadian infrastructure—destroying bridges, railways, and communication lines to disrupt British logistics and troop movements. These sabotage plans echoed tactics later used in World War II, where targeting supply lines proved crucial. The U.S. military understood that striking quickly at these choke points could paralyze an enemy’s ability to reinforce or resupply. This focus on infrastructure reveals how modern warfare increasingly relied on disrupting networks, not just winning battles on the ground (via CBC Archives).

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6. Naval Battles in the Atlantic

War Plan Red: The Forgotten U.S. Plot to Battle Britain
Image Source: Wikimedia Commons.

War Plan Red’s architects recognized that control of the Atlantic Ocean would be crucial in any conflict with Britain. The plan called for aggressive U.S. naval action to challenge the Royal Navy, enforce blockades, and cut off British reinforcements and supplies from reaching Canada. Maritime supremacy was seen as a linchpin for victory, echoing the global naval strategies of the era. These ambitious operations reflected the fierce competition for sea power that defined much of early 20th-century military thinking (via U.S. Naval Institute).

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7. Air Power and Early Air Force Concepts

War Plan Red: The Forgotten U.S. Plot to Battle Britain
Image Source: Wikimedia Commons.

War Plan Red acknowledged the emerging potential of air power, even as military aviation was still developing. The plan proposed using bombers for strategic strikes on enemy infrastructure and troop concentrations—an approach that foreshadowed the massive air campaigns of World War II. Although limited by technology at the time, this reliance on aerial attacks marked a shift in military thinking (via Smithsonian National Air and Space Museum).

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8. War Plan Red’s Secrecy and Declassification

War Plan Red: The Forgotten U.S. Plot to Battle Britain
Image Source: Wikimedia Commons.

For decades, War Plan Red remained one of America’s most closely guarded secrets. It wasn’t until the 1970s that the plan was finally declassified, revealing its details to a stunned public and sparking a wave of historical research. The plan’s disclosure led to renewed curiosity about U.S.-British relations and the hidden history of military contingency planning (via U.S. National Archives).

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9. Political Fallout and International Relations

War Plan Red: The Forgotten U.S. Plot to Battle Britain
Image Source: Wikimedia Commons.

The revelation of War Plan Red’s existence caused a wave of diplomatic embarrassment and awkward explanations between the U.S. and U.K. Both governments quickly issued reassurances that the plan was a relic of a bygone era, emphasizing their enduring alliance. The incident echoed similar disclosures of secret military schemes, such as Britain’s plans for Germany or the U.S. “War Plan Orange” for Japan. Ultimately, the episode highlighted how strategic paranoia once drove even close allies to prepare for the unthinkable (via BBC).

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10. How War Plan Red Compares to Other War Plans

War Plan Red: The Forgotten U.S. Plot to Battle Britain
Image Source: Wikimedia Commons.

War Plan Red was remarkable for its detail, rivaling other major U.S. contingency plans like War Plan Orange (Japan) and War Plan Black (Germany). Each plan reflected meticulous analysis—mapping enemy strengths, logistics, and invasion routes. However, War Plan Red stands out for its audacity: envisioning a massive land and naval campaign against a global superpower and its North American dominion (via The National WWII Museum).

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11. Lessons Learned and Legacy

War Plan Red: The Forgotten U.S. Plot to Battle Britain
Image Source: Wikimedia Commons.

War Plan Red’s existence underscores the importance of strategic foresight, even when scenarios seem improbable. The plan shaped future U.S. military doctrine, emphasizing preparation, flexibility, and the value of contingency thinking. Modern defense planning still draws on this legacy, crafting responses for emerging threats—however unlikely. Its story is a reminder that careful, sometimes uncomfortable planning is a cornerstone of national security (via Army University Press).

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12. War Plan Red in Popular Culture

War Plan Red: The Forgotten U.S. Plot to Battle Britain
Image Source: Wikimedia Commons.

War Plan Red has captured the imagination of historians and storytellers alike, surfacing in books, documentaries, and even alternate history fiction. Its audacity and secrecy have made it a fixture in discussions about “what if” scenarios and military intrigue. Documentaries such as CBC’s “The American Plan to Invade Canada” have brought its story to a wider audience.

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13. Could War Plan Red Have Worked?

War Plan Red: The Forgotten U.S. Plot to Battle Britain
Image Source: Wikimedia Commons.

Modern historians and military analysts generally agree that War Plan Red would have faced enormous challenges in practice. The logistics of invading Canada, securing vast territories, and facing the Royal Navy would have stretched U.S. resources to the limit. Many experts argue that the plan’s success was doubtful, especially considering Britain’s global reach and alliances. Its value, instead, lay in forcing military planners to consider the complexities of large-scale operations (via HistoryNet).

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14. Legacy of War Plan Red

War Plan Red: The Forgotten U.S. Plot to Battle Britain
Image Source: Wikimedia Commons.

War Plan Red stands as a remarkable reminder of the unpredictable twists in international relations and the necessity of strategic foresight. Although never enacted, its existence reveals the climate of uncertainty that shaped early 20th-century military thinking and the lengths nations go to prepare for every possibility. Today, War Plan Red fascinates as both a historical curiosity and a valuable lesson in contingency planning—reminding us that yesterday’s allies could, under different circumstances, become tomorrow’s rivals.

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