Editor’s Note: John Avlon is a CNN senior political analyst and anchor. He is the author of “Lincoln and the Fight for Peace.” The views expressed in this commentary belong to the author. View more opinion at CNN.

CNN  — 

Seventy-five years ago this week, Secretary of State George Marshall gave a graduation address that changed the world.

America and its allies had won the Second World War. Veterans were attending college on the GI Bill and many citizens felt entitled to a peace dividend. But on June 5th 1947, the former general came to tell the graduates at Harvard University that the war was not really over.

John Avlon

Threatened by Soviet aggression, Europe “must have substantial additional help, or face economic, social and political deterioration,” Marshall warned. “The United States should do whatever it is able to do to assist in the return of normal economic health in the world, without which there can be no political stability and no assured peace.”

Marshall was proposing something unprecedented: that America help rebuild its enemies as well as its allies. This was the opposite of reparations. It was an investment in peace.

But words are cheap. US President Harry Truman understood that the American people would need to be sold on the idea of spending more money to secure the peace after years of war.

Republicans had control of Congress, so the effort had to be bipartisan from the start. Truman and Marshall cultivated the Chairman of the Senate Foreign Relations Committee, Arthur Vandenberg. At first, he balked at the idea of spending more than 10 cents out of every dollar in the federal budget back in Europe.

But Vandenberg — who’d been an isolationist until the attack on Pearl Harbor — understood that partisan politics ought to end at the water’s edge. So, he set about winning over his fellow Republicans. He insisted that the Marshall Plan be run like a business, with strict accounting of expenses, in partnership with other allied nations. A surge in Soviet aggression created a sense of urgency.

The Marshall Plan was the olive branch that complemented the arrows of the Truman doctrine: “to support free peoples who are resisting attempted subjugation by armed minorities or by outside pressures.”

It ultimately passed with 69 votes in the Senate. Within months there were ships delivering food and medicine, as well as funding to rebuild dams, bridges and buildings. Europe was stabilized by economic interdependence, spurring growth while taming inflation. Political moderates rather than extreme parties rose in parliaments. In the end, security was strengthened by the creation of NATO, while trade agreements created the foundation for the European Union.

Now you might be asking why the Marshall Plan should matter to you today?

Because it turned enemies into allies and dictatorships into liberal democracies.

Because it reminds us that America’s greatness is connected to our goodness.

And because it helped establish 75 years of relative peace and prosperity in western Europe.

In recent years, we’ve learned the dangers of taking our democracy for granted — and in recent months we’ve learned the wisdom of those organizations established by America and its allies to win the peace after World War II.

Vladimir Putin’s invasion of Ukraine should have shattered any fashionable illusions about isolationism or the end of history. It should also remind us that geopolitical bullies only respect strength. That’s why collective security agreements work. Just ask traditionally neutral nations like Finland and Sweden why they want to join NATO now.

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    There are already calls for a new Marshall Plan to rebuild what has been destroyed in Ukraine – and signs of renewed solidarity among allies with a determination that Russia remain isolated.

    But the best way to honor the Marshall Plan is to recognize that peace must be waged unceasingly. We cannot wisely retreat from the world because what Marshall, Truman and Vandenberg understood is still true — if you don’t win the peace, you don’t really win the war.