How long could Canada hold off an invasion from the U.S. if they decided to declare war?

Depends, if the US is already mobilized, then you can expect that most of Canada would be, more or less, occupied in a week. If the US hasn't mobilized and just declared war, then Canada can be expected to be occupied in under 3–4 weeks.

This answer is based on if NO other nation is involved.

EDIT: Quora made this answer collapse for some reason, so im going to add more

This is going how to play out,

The US Navy will bombard coastline cities and obliterate the entirety of the Canadian "Navy"(said that because they are VERY weak compared to the US)

In the Air, The US Air force would most likely first Bomb the Canadian Air bases, and Destroy any Aircraft that manages to take off, After that they will attack Industrial bases(though I question this, as the Army would most likely just take it undamaged) and Attack Government buildings.

On the land, the US army will literally destroy the Canadian forces, which have a total of 40,000 Soldiers vs the US's 1,280,000 Active personnel and about 800,000 Reserve Personnel. So yeah, Rest in Peace Canadians.

Politically, If the US populace wouldn't mind killing their Canadian friends, the world will, they either declare war, or place sanctions, therefore destroying the US economy, which weakens it, which the world can then declare war on the weakened US. Rest in PIECES Americans.

I'm really getting sick and tired of repeated questions about the U.S. invading/conquering/pillaging Canada. Is this really what our neighbours spend their time contemplating?? I see them every bloody day. It really speaks to arrogance and self-centeredness let me say...

Let's get something straight. OF COURSE you could occupy/defeat us in conventional warfare BECAUSE YOUR POPULATION IS 10 TIMES OURS AND YOU HAVE A MEGA-OVERSIZED MILITARY TO BOOT! So posing this question is really just an excerise in arrogance.

HOWEVERRRRR, let's think about Vietnam, let's think about Iraq.... Just because we are a much smaller country, with a much smaller military (in PEACETIME, for those who don't know it, we raised a very large military in wartime... one of the biggest in the world during the world wars) DOESN'T MEAN YOU WOULD BE VICTORIOUS IN THE END. Yes, you could decimate our conventional defences and occupy BUT you would make enemies around the world and you would have a lot of Canadians (and their friends and sympathizers around the world) SABOTAGING YOU and working against you behind the scenes. Remember how well you did against guerrilla fighters in those other wars? Didn't come out so clean in the end did it? And guess what, those countries didn't have MILLIONS OF THEIR CITIZENS (who by the way can quite easily pass as your average American if they want to...) LIVING IN THE U.S. AND BEING INTEGRATED INTO YOUR COUNTRY AND ITS COMMUNITIES AND COMPANIES (even its government.)


And by the way, if there's any country in the world that has had your back these last 150 years, it's been Canada, even though you piss us off plenty! You ought to think about that before posting such arrogant stuff about how you'd happily invade and murder our people. :p


I'm Canadian, and I'll tell you right now. ZERO chance of staging off an invasion from the USA. We have the longest shared and undefended border in the world, if every Canadian man, woman and child were sent to guard the border...which is like 4000 km long, we would STILL have huge gaps along the border.

On the flip side, If we were invaded by the USA there would ZERO chance of the USA actually "taking control," of Canadian cities.

Canadians would fight in small, gorilla style bands. In the day, we'd smile and nod to our American oppressors, and at night...hurl rocks, use pitch forks, shotguns, baseball bats etc.

It's one thing to invade a contry,

It's a totally different story trying to control and rule a foreign country.

How successful was England vs the Scots? For a 1000 years the English could never gain real control over them.

Additionally, the USA would have to contend with a barrage of near daily terrorist attacks. Remember that unguarded 4000km long border? Yeah, well...all you have to do is walk across a cornfeild and your either in Canada or the USA.

So, if the American navy actually did bomb Canadian ports, they can expect the see from us. Canada DID burn down and capture the White House :-)

No, we could not. Canada has about 100,000 troops (active and reserve) while the US has over a million. Canada has 78 combat aircraft, the US has 3000 plus. Canada has 100 tanks, the US has over 5000+. Canada has some 40 ships, the US has over 400.

However, if the US did invade, they were be persona non grata with most of the western world and would NEVER be trusted again. The US would lose $185 billion in trade with Canada annually and over 40 percent of its oil supply.

The Canadian military might not be able to defeat the American military but we could do beaucoup damage to the infrastructure of the oil industry and pipelines in Canada, making it very costly for the US to repair them.

Canada is an ally of the US, and in fact there is often a Canadian officer holding the keys to the US nuclear response in SAC HQ awaiting the Presidents order. So, we would have LOTS of warning if the US relationship with Canada was going sour - they would have to lose us s allies first.

Depends on the strategy, I suppose.

If we tried to fight head on then I think it's fair to say that Canada would be obliterated. Things get more interesting, however, if we start fighting with fabian tactics, or guerrilla warfare. Pulling them north, into places where the advantage lies firmly with the defenders, and I figure we'd last long enough for other issues to arise with the war.

International opinion, for one, would castigate the USA and some would likely try to aid Canada, directly or indirectly, as the defenders. Some countries might try to take advantage of the war to attack or sabotage the US

Worse case scenario? Hello WW3.

But it's an academic point, since the invasion of Canada would be a terribly stupid and irrational move for the US. There's no real advantage for them to do it, many reasons not to, and whatever they gain from the excursion would be outweighed by the incredible cost.

The question seems to have a blind spot though.

Besides the fact that there'd be no surprise... Canadian Forces staff are embedded at all levels with the US in North American defence posts such as NORAD, and in many of their bases here and abroad in exchange programs , training, and joint operations.

The question isn't how long Canada could hold off.

Because of one word: NATO

See Member countries

An attack on one is an attack on all of the 26 other member countries , who must by treaty, come to the defence of the one attacked.

So it's not just Canada, it's:

Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, the United Kingdom, Greece, Turkey, Germany, Spain, the Czech Republic, Hungary, Poland, Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia, Slovenia, Albania, Croatia, and Montenegro.

But that's not the worst of it. Think of the "No soup for you" Soup Nazi in Seinfeld, and just imagine the service that first American tank is going to get when he pulls up to the Tim Horton's drive through window.

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