Empires grow for many reasons. While it's easy to be cynical about high motives, they can't be ignored. It was not so long ago that most Americans thought it self-evident that most nations of the world would be better off under the tutelage of the United States. We could teach them the secrets of economic development while initiating them into the arts of self government.
The Vietnam War had a pivotal effect on American life. Prior to that war we had entered an unprecedented period of economic growth. There could be no doubt of the future. We were going to the Moon. Communism would be contained by military force; meanwhile, the economic machinery which we now understood—Keynes was on the cover of Time's last issue for 1965, and even Richard Nixon said, "We are all Keynesians now"—would generate ever-increasing wealth, which we would use to eradicate poverty, ignorance, and want, first from the United States, then from the world.
We could do anything, and only a few like Russell Kirk muttered darkly about hubris, nemesis, and catastrophe. Time summarized it all in December, 1965: "If the nation has problems, they are the problems of high employment, high growth, and high hopes."
We had similar optimism about foreign affairs. Kennedy had announced that we would bear any burden and fight any foe to advance the cause of freedom. Was the Diem regime in Vietnam corrupt? There could be only one answer to that. Diem had invited us there, but he was not worthy; bring him down, to make room for genuine democracy. We were not merely containing communism, we were building nations.
We poured forth blood and treasure, and sent conscript soldiers to die in places whose names they could not pronounce.
We also made promises we did not keep, as H. Kaplan, retired from the U.S. Foreign Service, reminds us.