A long time ago, a power-mad tyrant established himself as the autocratic ruler of a democratic country.  He crushed dissent within his own country, and then he began to make demands on other countries.  At first, he went after small, weak countries.  Often, he would take small parts of that country and annex them to his country.  These were minor countries on the world stage, so most other countries would not stand up against him for those insignificant places.

Other countries argued, "Why should we stand up for these little countries?  This will only result in a major war.  Who wants to risk another world war?"  So no one wanted to stand up to him.

Then one day, the tyrant changed his ways and simply invaded another country.  There was a cover story giving a phony reason for the invasion, but everyone knew that it was false.  The world knew that the invader would win, but everyone hoped for a miracle.

As you've guessed, that narrative could describe Hitler in the 1930s or Putin now, given that the parallels between the current Russian invasion of Ukraine and the Nazi invasion of Poland are many.  What's different is that there was an optimism about the future at the start of World War II.

Poland, Denmark, Norway, Holland, Belgium, and France all fell quickly to Hitler, yet those countries did not completely give in.  They each formed a "government in exile" in another country, typically Britain.

Not only that, but expatriates who were able to make it to Britain formed their own fighting units, such as the "Free French" brigades and the Polish pilots who fought in the Battle of Britain.  And don't forget the resistance fighters who waged unconventional war inside those countries.  Each of these countries' governments and people expected that, one day, they would be able to return to their own land.

Image: Polish flyers (plus one Canadian) in the Battle of Britain.  Public domain.

But where did that vision come from? Mind you, this was before the NATO alliance.  It was before the United Nations was formed.  And it was before the United States entered the war.  By the fall of 1940, the only intact country fully opposed to Hitler's Third Reich, which stretched across most of Europe, was Britain.  It was a pretty small alliance against such an overwhelmingly powerful foe.  Britain had not yet won the Battle of Britain, an air battle.  Neither the British nor these governments-in-exile had any idea how long it would take to defeat Hitler, but they were determined to try.

The ability of those governments-in-exile to continue the fight depended on three primary things:

1. Shelter: A country willing to shelter and support a government in exile.  That country would be automatically targeted as Russia's enemy.  Britain was already at war with Germany, so it had nothing to lose by sheltering governments-in-exile.
2. Willingness: A cultural willingness to fight regardless of the strength of the enemy's forces.  Churchill's speeches did much to strengthen his countrymen's resolve.
3. Potential Leverage: A sense that a much larger military force just might be brought to bear in the near future.  Britain worked for the U.S.'s participation, and it finally came about.

This is highly speculative, but if Russia were to defeat Ukraine in the near term, I think Poland might be the best bet for a government-in-exile.  Let's evaluate those three criteria:

1. Concerning shelter, it is possible that a Western NATO country might be able to step into this role, but thus far no such country has stepped forward.  Currently, though, Poland is allowing many Ukrainians fleeing the war to settle in their country.  The Poles might accept a government-in-exile.
2. Concerning willingness, Poland has a history of standing up to the Russian bear near the end of the Cold War.  It's also a potential target of Russia because it's adjacent to Russia's ally, Belarus, and because Russia owned Polish land in the past.
3. Concerning leverage, Poland is part of NATO.  If the NATO treaty is to be believed and enforced, then war between Russia and Poland would bring the full force of that alliance to bear (pun intended).

It may be that the war will end with Russia retreating.  However, if the Russians prevail, there is a strong possibility that Putin will follow Hitler and expand his wars of conquest.  If that turns out to be true, it would be better for the world to stand against Putin now than a much stronger Putin in the future.  And that's why the possibility of continuing the fight should be considered.