Admittedly, the United States isn’t exactly on the BFF list for too many countries. Being the leader of the Free World may garner a certain measure of respect but not necessarily a lot of affection.

For two countries, however, the relationship with the USA goes well beyond diplomatic niceties. The United Kingdom has claimed a “special relationship” with the United States since the days of Winston Churchill and Franklin D. Roosevelt. Canada also lays claim to a unique level of friendship. The 5,525-mile (8,892-km) border between the two countries is the longest unguarded international border in the world, attesting to the high level of trust between the neighboring nations.

So why did the United States develop a top-secret plan to invade its neighbor to the north and to fight an aggressive trans-Atlantic war against its closest ally? The answer to this surprising question is found in War Plan Red.

When the Military Plans for the Unthinkable

The military is always at its best when it can focus its planning on an enemy. In the days following World War I (aka “The War to End All Wars”) it was a little difficult finding anyone who fell into that category. At least, it was hard finding any potential adversaries who posed a serious military threat.

Not wanting their planning skills to grow rusty, the Department of War (later renamed Department of Defense) focused its attention on a hypothetical military problem and tasked its officers with developing an appropriate plan.

The practice of planning against an unlikely scenario is not unique. The U.S. military has even developed contingency plans for a hypothetical zombie apocalypse.

Widespread fear of zombies was still decades in the future in the years between the world wars, however. When military strategists turned their ever-keen minds on a worthy adversary, they chose the United Kingdom. Perhaps one or two of them still harbored a bit of a grudge over that little “it’s complicated” point in the nations’ relationship back in 1776.

An Army spokesman in 1928 admitted, “A war with Great Britain seems highly improbable in the near future.” It was useful, however, to think through the implications of that scenario. The British navy was the only force in the world capable of attacking both the continental United States and its dependencies in the Caribbean and the Pacific.

The Birth of War Plan Red

The result of this planning was “The Atlantic Strategic War Plan,” better known as “War Plan Red.” The nickname arose out of the use of colors to designate the different players in a multi-front war. As shown on a map, the United States was “Blue.” The United Kingdom and the nations that fell under the British Empire were “Red.”

War Plan Red was approved by Secretary of War Patrick J. Hurley and Secretary of the Navy Charles Francis Adams in 1930. It was updated in 1934 and 1935. The entire declassified plan is accessible here.

The Hypothetical British Attack

For planning purposes, it was assumed that the U.K. would be the ones picking a fight. Perhaps one or two of them still harbored a bit of a grudge over that whole Tea Party thingy. According to the strategists of War Plan Red, however, the more likely casus belli of hostilities would stem from “constantly increasing Blue (American) penetration and expansion into regions formerly dominated by Red trade, to such an extent as eventually to menace Red standards of living and to threaten economic ruin.”

They concluded that the U.K. would be left with no other choice than to eliminate America as a commercial threat by destroying American merchant shipping and seizing overseas possessions, including control of the Panama Canal.

For planning purposes, the scenario assumed the Brits would focus their attack on the industrial centers in the north. To do this, they would send troops through the Montreal-Quebec region of Canada to capture or destroy vital American war industries. Ground attacks would be coupled with sustained bombing campaigns against major cities including Washington, New York, and Pittsburgh.

At this time, Canada was still part of the British Empire, so it was assumed it would rally to the saber-rattling of the Crown. Its proximity to the United States put it in an ideal position to cripple American war production by seizing the Great Lakes waterways and cutting off the majority of U.S. iron ore transport.

The Global Dimensions of the Conflict

While the U.S. was still trying to respond to the surprise Canadian hostilities, the British navy would be hard at work targeting American interests beyond the continental United States. The Panama Canal, American islands in the West Indies, and the Philippines would fall with assistance from other British colonies including Australia and New Zealand.

British intelligence was expected to find sympathetic partners in Mexico and Argentina who could provide intelligence and assist with propaganda efforts. Even limited Mexican troop movements near the Rio Grande could force the United States to divert valuable military resources to its southern border.

America’s Counterattack: Invading Canada

The rapid success of Canada and the U.K. against the United States was not entirely unrealistic. Although the U.S. had the world’s largest military at the end of World War I, it rapidly demobilized afterward. America would therefore begin the war with a smaller navy and a much smaller army than its potential enemies.

In the summer of 1930, the U.S. Army within the continental United States consisted of just over 100,000 officers and men. Additional forces would need to come from the National Guard and the Organized Reserve, and even then planners warned that shortages of equipment and supplies would pose serious challenges.

To buy time for America’s powerful industrial base to mobilize, War Plan Red proposed a preemptive invasion of Canada, code-named Crimson. The full text of the plan to invade Canada can be read here.

One key target would be Halifax, Nova Scotia. The plan called for an amphibious assault on the city. If the attack failed, Halifax was to be destroyed in order to deny Britain a major North Atlantic naval base.

The 1934 revision of the plan even envisioned the immediate use of poison gas combined with strategic bombing of Halifax to cripple British naval support in North America.

Maine would serve as a critical staging ground for American operations. From there, U.S. forces could isolate Quebec and Montreal, strike Halifax, and seize important infrastructure such as the Niagara Falls hydroelectric facilities.

Real-World Preparations

Although War Plan Red was largely hypothetical, the United States did take some real-world steps to prepare for a potential conflict. In 1935, the War Department sought funding to build several border air bases capable of launching surprise attacks on Canadian airfields.

General F.M. Andrews testified before the House Committee on Military Affairs in February 1935 and attempted to reassure the legislators: “It is not believed that Canada unless forced to do so would ever join a coalition against the United States, but if she were part of such a coalition, air force operations from a base in the Great Lakes area would be capable of dominating the industrial heart of Canada.”

Despite the controversy, Congress passed legislation authorizing the construction of air bases along the border. That same year the United States conducted its largest peacetime military maneuvers to date, involving tens of thousands of troops near the Canadian frontier.

The Final Stages of the Hypothetical War

Once American industry had fully mobilized, the focus of the conflict would shift to naval warfare. The U.S. Navy would attack British shipping in the Atlantic and the Pacific while defending the strategically vital Panama Canal.

U.S. forces would also seize key British possessions in the Caribbean including Jamaica, Bermuda, and the Bahamas. Cutting off British access to food and raw materials from across the Western Hemisphere was expected to force the empire to surrender.

Why the Plan Was Abandoned

Fortunately, War Plan Red never had to be tested. By the late 1930s the global strategic landscape had changed dramatically. The rise of Nazi Germany and Imperial Japan created real enemies that demanded attention.

In 1938 Major-General Stanley Embick noted that the entire premise of the plan had become unrealistic. American naval planners had long argued that Japan—not Britain—posed the most serious threat.

When World War II broke out in 1939, planning for a war with Britain was quietly set aside. War Plan Red remained classified until it was finally declassified in 1974.

---