For the past century, the United States and Canada have been the best of friends, and war between them was unimaginable. Before that, however, it was a possibility that was always at the back of mind for military strategists on both sides of the borders—in no small part because the two had gone to war before.
Today, however, anxieties have flared. President Donald Trump has spoken openly about extending the borders of the United States all the way to the high Arctic, insisting that Greenland would be safer as a U.S. territory, while Canada could join the union as the 51st state. This will happen, Trump insists, through peaceful means.
Canadians aren’t so sure. Shortly after Trump’s inauguration in January, Google searches mentioning the term “invade Canada” skyrocketed. Canadian media have been interviewing military experts to game out what such an invasion would look like. Canadian gun enthusiasts are preaching the need for their fellow citizens to arm themselves, just in case.
The actual prospect of war between the two allies remains exceedingly unlikely. And yet strategic thinkers on both sides of the border are likely contemplating what such a conflict would look like.
Wargaming and contingency planning is, after all, not the art of planning for the most likely outcome but drawing up plans for every conceivable scenario—including the unlikely.
So what might it look like to prepare for war in North America?
A engraving depicts the War of 1812 as the British sail up the Chesapeake to attack and set fire to the new U.S. capital of Washington, D.C.Bettmann Archive/Getty Images
The only time the United States properly went to war with its neighbor was the War of 1812, when the young country waged a chaotic and shambolic fight against Great Britain and her territories.
“Our wrongs have been great; our cause is just; and if we are decided and firm, success is inevitable,” wrote Henry Clay, the speaker of the House of Representatives at the time, in declaring war against Great Britain over a host of maritime issues, including its impressment of U.S. sailors. Clay and many of his fellow legislators believed that invading their northern neighbor was the natural extension of their own revolution decades earlier. They expected many of the people they saw as fellow Americans would greet them as liberators.
It was not to be. The war consisted mostly of a series of cross-border skirmishes along the Great Lakes and in northern Maine, and a series of naval battles along the Atlantic coast. The war came to a dramatic climax when British troops sailed up the Chesapeake, pushed into Washington, D.C., and stormed an abandoned White House. The troops ate President James Madison’s dinner, drank his wine, and proceeded to set fire to much of the capital.
When both sides met in Belgium for peace talks, the British accused the United States of declaring the war with “a spirit of aggrandizement” and seeking the “conquest of Canada, and its permanent annexation to the United States.” The U.S. representatives denied the charge, but they were undermined by the statements of their own generals.
The peace deal returned the borders to much as they were before the war—a considerable victory for Madison’s administration. “Some say that the War of 1812 is the closest Canada has had to its own war of independence,” historian Kevin Lippert wrote in War Plan Red.
The anxieties would diminish over time, but the prospect of another war was considered extremely likely for much of the 19th century.
While Britain remained officially neutral during the Civil War, it was embroiled in a diplomatic crisis when Union ships seized two Confederate envoys sailing to London on an English ship in 1861. The prospect of war was so acute that Canada’s governor moved troops and supplies to the border. Cooler heads, ultimately, prevailed.
But things grew tense once more after a series of raids—and a high-profile assassination—were carried out by the New York City-based Fenian Brotherhood in the 1860s and 1870s. The Irish militants hoped their incursions into Canada would pressure the British to withdraw from Ireland.
A mounted Canadian police officer Universal History Archive/Universal Images Group via Getty Images
The prospect of invasion was top-of-mind for Prime Minister John A. MacDonald, the first leader of the new Canadian confederation, who immediately set out preparing Canada for such an invasion. He began constructing an east-to-west railway, designed to carry troops from one coast to another, should it be necessary. He established the North-West Mounted Police (later the Royal Canadian Mounted Police) to operate as a kind of permanent militia to protect against prairie criminals, put down Indigenous sovereignty, and guard against possible invasion by U.S. forces.
In the ensuing years, however, the prospect of war became less and less likely. A series of trade conflicts in the late 19th century raised the prospect that Washington was using economic coercion to force a union with Canada, though the idea of a fresh war became increasingly laughable.
The shared sacrifice of both nations in World War I built a bond across the border which made the prospect of armed conflict unthinkable.
And yet, military strategists on both sides of the border began thinking it.
An image from War Plan Red by Kevin Lippert.Princeton Architectural Press
In 1921, a Canadian lieutenant colonel named James “Buster” Sutherland Brown began preparing Defence Scheme No. 1. While the strategy was ordered by his superiors, it was not an officially sanctioned plan, for obvious reasons. It was a strategy to invade the United States.
Taking advantage of the long, lightly-defended border, Canadian forces would organize a five-front push south, aiming to seize and destroy vital rail and communication lines to weaken the ability of the United States to wage war. From there, the Canadian forces would quickly retreat and regroup behind defensive lines. Canada’s “goal was to dance like a butterfly and sting like a bee,” Lippert wrote. It was a strategy to buy time for British reinforcements from around the globe.
The plans were so controversial, however, that they were ordered destroyed not long after they were written.
Less than a decade later, American strategists began developing the mirror image of these plans. Titled War Plan Red, it considered a global conflict between the United States (“blue”) and the United Kingdom (“red”). In the plan, Canada was codenamed “crimson.”
The plan goes into particulars about the pitfalls of such an invasion: Nova Scotia’s many lakes would be useful for Canada’s defensive lines; the border town of Sault Ste. Marie, Ontario, is “sparsely populated [and] poorly developed”; Vancouver, British Columbia, has adequate communication and rail links to facilitate the arrival of British reinforcements, and so on.
The war plans make clear that if America hoped to win a war against the British Empire, seizing Canada quickly and decisively would be imperative. That could be achieved, the U.S. strategists concluded, by seizing the territory between Quebec City and Toronto—effectively severing the country in two, disrupting communications, and providing control of Ottawa, the capital—and sailing to seize the port of Halifax.
While the plans are bullish on American victory, the Joint Chiefs highlight one possible Achilles heel for the United States: the Panama Canal. “The importance of the Canal to BLUE is heightened by the extreme importance which RED would attach to its capture,” the plans read.
These plans would not be published until 1974, although they were not kept entirely secret at the time. Plans to establish clandestine air bases along the Canadian border, camouflaged as civilian airports, were accidentally released in 1935, earning an immediate rebuke from President Franklin Delano Roosevelt.
Canada was inclined, the New York Times reported at the time, to “not take the matter seriously.”
The U.S. Coast Guard icebreaker Polar Sea.U.S. Coast Guard
If the prospect of cross-border invasion was ever put to rest, it was in Ogdensburg, New York, in 1940. The agreement signed there by the United States and Canada committed both sides to being mutually responsible for “the defense of the north half of the Western Hemisphere” and set up the Permanent Joint Board of Defense, responsible for jointly managing continental security.
From that point on, the militaries, war industries, economies, and strategic outlooks of the United States and Canada would be intentionally and deeply integrated. In the ensuing years, this shaped the creation of the North American Aerospace Defense Command (NORAD) and the North Atlantic Treaty Organization.
NORAD, in particular, established one of the world’s most impressive and far-reaching air defense systems. Over the years, the system expanded and upgraded to shield the entirety of the U.S. and Canada from all manner of threat, including nuclear weapons. That meant U.S. security was intrinsically linked to the fate of the Canadian military.
Throughout the Cold War, the Pentagon and think tanks like the RAND Corporation often strategized and simulated the prospect of European nations falling to Soviet influence. But so solid was the U.S.-Canada relationship over this era that it does not seem that the prospect of Canada becoming a liability, even a threat, to the United States was contemplated; if it was, those documents have yet to be declassified. (Although the CIA did actively monitor Canadian leftist groups as domestic security threats.)
“I am aware of contingency planning in relation to other NATO allies turning Communist,” Brian Morra, a former U.S. intelligence officer who was intimately familiar with contingency planning during the Cold War, told Foreign Policy. “I am not aware of any contingency planning for military action against Canada.”
Over this time, however, one area complicated things: the Arctic.
From its inception as a country, Canada paid little attention to the high north. The Cold War, and Russia’s proximity, pushed Ottawa to install a network of early warning radars throughout its northern territories. As one 1980 report produced by Canada’s Department of National Defence noted, “[T]he compulsions of power politics severely limit Canada’s ability to let her negligence pose a danger to the United States.”
While the Arctic was seen as a critical piece of continental security, the United States and Canada had a fundamental disagreement about who was actually responsible for it.
Canada has always held that the waters which jut between the rocky archipelago of its northern territories are its exclusive sovereign waters. The United States, on the other hand, considers them “international straits.”
The 1980 Canadian report warned that “the greatest threat to Canadian authority in the arctic may well come from the United States.” Five years later, the U.S. Coast Guard icebreaker Polar Sea sailed through the Northwest Passage without informing Canada, sparking a diplomatic row.
The issue was put to rest in 1988, when the United States agreed to seek Canada’s consent before sailing through the Arctic, but the agreement did not settle the question of whether the waters are Canadian sovereign territory.
If tensions further increase between Canada and the United States in the coming years, it will likely be on the question of Arctic sovereignty.
To date, Trump has openly suggested acquiring three countries: Panama, due to its control of the Panama Canal; Greenland, and Canada, which control the eastern entry to the Northwest Passage.
While the United States may not be drafting plans for a full-scale invasion of Canada, there’s good reason to think the White House may be gaming out a new bid to assert control of those critical shipping lanes.
“The logic chain is that if Greenland and the Arctic are strategically important and Denmark can’t defend Greenland, then it is America’s responsibility to defend Greenland but not for free,” Morra said. “Trump is using a similar logic chain for Canada. He genuinely believes that a country that cannot defend itself is not a real country.”
If there are war plans for a surprise U.S.-Canada conflict, they are unlikely to see the light of day in this decade—perhaps not even this century, if ever.
But one group of strategic planners are much more public about their own efforts to consider continental war.
The Miniatures Page, which describes itself as “the home of miniature wargaming on the internet,” is a meeting place for history geeks who enjoy gaming out real and imagined conflicts—like the Pacific theatre in World War II or an alternative history where Russia invaded Alaska during the U.S. Civil War.
Conversation on these forums in recent months has turned to the possibility of the United States invading Canada. Earlier this year, the users considered one illustration of how the first two days of this hypothetical fight. It’s this kind of unconventional and unpredictable conflict that wargamers normally love.
“It could make for a fantastic game, I suppose,” one Canadian user wrote. But they went on to recall the century of shared sacrifice and brotherhood between both countries, from the beaches of Normandy to the skies over Kosovo to the desert of Kandahar; “our connectivity is historic, omnipresent, and envied by the world,” they added.
“I wouldn’t be playing it, even in fun.”
