World War II was America's last "good" war. It was "good" because the main enemy, Adolf Hitler and his Nazi regime, were widely known to be evil -- long before the full story of the Holocaust was revealed.
The war also good because it ended with unconditional surrender by our enemies. It didn't end in stalemate, defeat, or a hollow victory, as it did in Korea, Vietnam, Iraq (twice), and Afghanistan.
It was a high point of American history, which is why it is the subject of countless films, TV series, novels, and histories. It is why the veterans of World War II have been honored far beyond the relatively feeble recognition given to veterans of other wars.
But, in reality, World War II was a failed war because an enfeebled FDR, guided by the Communists in his administration, gave away Eastern Europe to Stalin. The giveaway was unnecessary. The U.S. had been relatively unscathed by the war; the Soviet Union's losses in life, property, and industrial capacity had been devastating. The U.S. (with Britain) was in a position to dictate to Stalin.
Think of all that has happened since FDR's giveaway, not the least of which is the war in Ukraine and the economic devastation it is visiting upon the West.
I once believed that World War II was necessary because, if the United States had failed to join it, Germany and Japan would have been able to encircle us. The mere presence of German and Japanese forces at our doorstep, and their ability to control our international trade, could have meant de facto submission to the authoritarian demands of Germany and Japan.
As it turns out, authoritarianism has overtaken the U.S. from within. So what was the point of fighting a "good" war?
Perhaps America's fighting spirit and fundamentally robust economy (which would eventually have recovered from the Great Depression) would have been proof against an invasion.
Economic isolationism was then far more viable than it is in the age of globalization. The rest of the world might have gone to hell in a handbasket, but America could well have survived intact, well-armed, well-clothed, well-fed, etc.
Perhaps the constant threat of invasion would have made Americans more united and more committed to the values that preserve liberty.
Perhaps the isolationists were right, after all.