The US Military’s Secret Plan to Invade Canada

President Donald Trump has spent much of the past two years talking about Canada in ways that would have sounded extraordinary during most of the modern U.S.-Canadian relationship.

He has repeatedly suggested that Canada could become the 51st state. And on Aug. 27, Trump went a step further in his ongoing dispute with the country, signing an executive order directing the federal government to rename Lake Ontario “Lake America.” The order requires federal maps and documents to adopt the new name, though Canada has no obligation to recognize it.

Canadian Prime Minister Mark Carney quickly rejected the change, saying Canadians would continue calling the lake by the name it has carried for centuries.

The rhetoric has added a strange new chapter to a relationship now defined by an escalating trade fight. Trump has previously floated eliminating the border altogether and making Canada a U.S. state, an idea Canadian leaders have repeatedly dismissed. But the idea of the United States absorbing territory north of the border has a much older history. America actually tried it.

When the United States went to war with Great Britain in 1812, American forces repeatedly invaded British Canada in an unsuccessful effort to conquer territory there. More than a century later, after the border had been peaceful for generations, U.S. military planners quietly worked out how they might do it again. The resulting document was called “War Plan Red.”

Completed in 1930, the plan envisioned a hypothetical war between the United States and the British Empire. Its color-coded vocabulary sounded almost like a board game: the United States was BLUE, Britain was RED and Canada was CRIMSON.

If BLUE went to war with RED, American planners expected CRIMSON to become one of the most important battlefields. The plan laid out how U.S. forces could invade Canadian territory, attack Halifax, seize critical infrastructure and prevent Britain from using Canada as a staging ground against the United States.

The Americans weren’t the only ones thinking about another war across the world’s longest international border. Canada had drawn up an invasion plan of its own.

The US Tried to Take Canada

When the United States declared war against Great Britain in June 1812, British-controlled Canada quickly became a major theater of the conflict. There were several causes behind the War of 1812, including British restrictions on American trade, the Royal Navy’s impressment of sailors and disputes over American expansion in North America. Canada also presented American leaders with an opportunity.

The U.S. Army’s official history describes the “invasion and conquest of Canada” as a major American objective during the war. It did not go particularly well at first.

American forces lost Fort Michilimackinac and surrendered Detroit in 1812. Attempts to cross the Niagara River and advance toward Montreal also failed. The following year, American troops captured York, modern-day Toronto, and Fort George, but other offensives ended in defeat. A later two-pronged push toward Montreal also collapsed.

The war eventually swung back toward the United States in some places, including victories around Lake Erie and the recapture of Detroit. Britain, meanwhile, brought the war directly into the American capital in 1814 when British troops entered Washington and burned government buildings, including the president’s mansion and the Capitol.

By the end of 1814, neither side had achieved a decisive victory. The Treaty of Ghent ended the war and essentially restored the North American political boundaries that existed before the fighting began. Canada remained outside American control. For more than a century, the United States would never again attempt to conquer its northern neighbor.

That did not mean military planners stopped thinking about it.

Canada Made a Plan of Its Own

One of the stranger chapters in U.S.-Canadian military history began in 1921. Canada’s military developed Defence Scheme No. 1, a contingency plan for what it might do if the United States invaded.

Lt. Col. James “Buster” Sutherland Brown, Canada’s director of military operations and intelligence, helped develop the plan using military intelligence reports and reconnaissance. Canadian records describe it plainly as a plan for a defensive war against an American invasion.

The scheme contemplated Canadian forces conducting counterattacks across the border while buying time for British reinforcements to arrive.

The Canadian Army’s official history says the plan was circulated beginning in April 1921 under a “Very Secret” classification. Work continued for several years, although it was never completed in final form and was no longer being updated after 1926.

By then, Canadian officials were increasingly skeptical that such a war would ever happen. One senior Canadian officer concluded in 1931 that relations between the countries had improved so much that an American invasion had become increasingly a political problem rather than a realistic military one.

The Americans, meanwhile, were preparing their own paperwork.

War Plan Red

During the interwar period, the U.S. Army and Navy developed a series of color-coded contingency plans for possible wars against different countries. One of them asked what would happen if the United States went to war with Great Britain.

Completed in 1930, Joint Board 325, Serial 435 became known as War Plan Red. The document remained classified until 1974 and is now preserved in the National Archives.

At the time, details of War Plan Red were known only to select military planners and a handful of top defense officials. Neither the broader public nor most political leaders were aware of its existence. Because American planners expected Canada to stay allied with Britain during such a conflict, neutralizing Canada became an important part of the plan.

The military looked at Maine as a potential staging area for operations against eastern Canada. American forces could use it to cut communications linking Quebec and Montreal with Canada’s Maritime provinces or launch attacks against Halifax and New Brunswick.

Halifax was particularly important because of its port and its possible value as a destination for British reinforcements crossing the Atlantic. The plan also looked at Canada’s industrial infrastructure. U.S. forces could seize power facilities around Niagara and cut Canada off from coal and other resources from the country’s western provinces, damaging its ability to manufacture weapons and supplies.

American planners even concluded that Canadian neutrality may complicate matters.

If Canada openly joined Britain, War Plan Red reasoned, the United States would have greater freedom to use its overwhelming manpower advantage against Canadian territory. The plan specifically contemplated American forces “overrunning CRIMSON.”

For a country that would eventually become one of America’s closest military partners, it was an extraordinary scenario. It was also still a contingency plan.

Was America Really About to Invade Canada?

War Plan Red is sometimes presented as evidence that the United States came close to launching another invasion of Canada. There is little evidence that it did.

Military organizations routinely plan for wars they hope will never occur. The years after World War I were particularly active for American military planners, who had seen firsthand what happened when the country entered a major conflict without years of preparation.

War Plan Red examined what the United States might do if another war with Britain were to occur. It was not an order from the White House to prepare for an imminent invasion. Even the National Archives, which preserves the plan today, describes it as an example of the U.S. military’s effort to remain prepared for possible contingencies during the interwar years.

Canada appears to have viewed its own American war plan in much the same way. By the late 1920s, Defence Scheme No. 1 had been allowed to fall out of date as the possibility of fighting the United States became increasingly remote. History was already pushing the two countries in another direction.

From Invasion Plans to NORAD

Less than a decade after War Plan Red was completed, Britain and Canada entered World War II. The United States followed in 1941, and Americans and Canadians found themselves fighting the same enemies.

By 1940, President Franklin Roosevelt and Canadian Prime Minister William Lyon Mackenzie King were already discussing the joint defense of North America.

The United States and Canada established the North American Air Defense Command in 1957 and formally approved the binational agreement the following year. Renamed the North American Aerospace Defense Command in 1981, NORAD continues to provide shared aerospace warning, aerospace control and maritime warning for the continent. Its commander answers to both the U.S. president and Canadian prime minister.

In 1812, American troops marched north hoping to conquer British Canada. In the 1920s, Canadian officers planned how they might fight their way into the United States during an American invasion.

By 1930, U.S. planners were identifying the Canadian ports, transport routes and infrastructure that they might need to use in the event of another war, and now the two militaries are in the same command centers, keeping an eye on the same skies.

War Plan Red never moved beyond the planning stage. Yet the fact that it ever existed shows the great change that has taken place in the strategic and diplomatic relationship between the United States and Canada over the last hundred years.

Although the plan originally expressed real concerns about the possibility of conflict and the need for military preparedness, today its legacy illustrates a shift from one based on suspicion and contingency planning to one characterized by lasting cooperation and alliance in regard to the defense of North America.