Something was lost when the World War II generation vanished from the halls of Congress.

Originally personified by young veterans like John Kennedy, Richard Nixon and Jerry Ford, who were elected to the House in the 1940s, the torch of memory was later held high by former Senate Republican leader Bob Dole (who suffered grievous war wounds with the 10th Mountain Division in Italy).

The 114th Congress in 2015 was the first in seven decades without a World War II veteran.

The most notable departure was Rep. John Dingell, who had been training stateside for an assault on Japan when Harry Truman dropped the atomic bomb. As a 16-year-old page, Dingell also was on the House floor in 1941 when a solemn Franklin Roosevelt told a joint session of Congress that the Dec. 7 attack on Pearl Harbor was “a date which will live in infamy.”

World War II, of course, still flourishes in popular culture, from the indelible fascination with Winston Churchill (“Darkest Hour”) to cinematic commemorations of cataclysmic events like Dunkirk and D-Day (“Saving Private Ryan”).

Watch: What You Didn’t See at Dole’s Congressional Gold Medal Ceremony

Lessons of history

But without firsthand knowledge, history blurs. All you are left with are simplistic metaphors about Munich and gauzy images of the Greatest Generation. Judging from the alarming rise of anti-Semitism, especially in Europe, even the lessons of the Holocaust risk being obliterated.

All this speaks to the enduring value of the National World War II Museum in New Orleans. Visiting the attraction (founded in 2000 as the National D-Day Museum) on a rainy Friday last week, I was gratified to see the exhibits clogged with tourists young enough to be two and three generations removed from the 16 million GIs who served in the war.

The featured exhibit — the “Arsenal of Democracy,” about the home front during the war — inevitably inspired musings about contemporary life and politics. Little of the presentation was heavy-handed (a persistent danger with contemporary museums), but it did offer reminders of the continuity of history.

During the 2016 campaign and afterward, Donald Trump embraced the slogan “America First,” heedless of its roots as the rallying cry of 1940s isolationists under the leadership of aviator Charles Lindbergh.

The museum offers a mock debate — through dueling film clips — of Lindbergh and Roosevelt arguing over America’s responsibility to a battered but unbowed Britain. Watching the handsome Lindbergh speaking with a clipped Midwestern accent, I realized that the facile parallels with Trump did not quite work.

What Lindbergh did anticipate, though, was Trump’s cynical worldview — that America has no obligation to uphold democracy, fight for human rights or battle injustice anywhere else in the world. It is Fortress America rather than Ronald Reagan’s “shining city on a hill.”

The problem with such go-it-alone nationalism is that it squanders America’s greatest asset, which is our history of moral leadership. From Lend-Lease aid to Britain to the Marshall Plan to rebuild Europe to “Mr. Gorbachev, tear down that wall,” this nation has tried — albeit sometimes in stumbling fashion — to uphold our democratic values.

The greatest moral failing on the home front during World War II was the forced internment of more than 100,000 Japanese-Americans. FDR’s 1942 Executive Order 9066, sending these citizens who had been accused of no crimes to bleak relocation camps, was an unconstitutional reaction to the bombing of Pearl Harbor.

The museum’s filmed recollections of those who were interned (including former Democratic Rep. Norm Mineta, who later became George W. Bush’s Transportation secretary) haunt me days later. The tiny detail that I found chilling was that the internees were allowed to bring only “one suitcase” as they were imprisoned behind barbed wire in their own country.

In 1988, Mineta succeeded in winning congressional passage of the Civil Liberties Act, which authorized $1.25 billion in reparations to compensate those who were interned. Joining Mineta in this crusade was former GOP Sen. Alan Simpson, who had met the future congressman during his wartime internment in Cody, Wyoming, through their shared passion for the Boy Scouts.

Avoiding a repeat

What gives this story contemporary urgency is the lingering potential for the similar demonization of American citizens who are Muslims. Remember that during the 2016 campaign, Trump made the inflammatory charge — contrary to all evidence — that thousands of Muslims were cheering in New Jersey after the Twin Towers were toppled in 2001.

Upholding the rule of law and democratic norms does not happen automatically. If Franklin Roosevelt — the president who articulated the Four Freedoms — could give in to panic after Pearl Harbor, then it remains frightening what could happen if there were ever a major terrorist attack with Donald Trump in the White House.

For me, the enduring message of the museum’s Arsenal of Democracy exhibit was the sense of shared sacrifice and national unity that prevailed after Pearl Harbor.

No other American war — including World War I — was waged without major internal divisions. But it was the righteousness of the struggle against Germany and Japan that inspired what should be remembered as America’s finest hour.

As new generations visit the National World War II Museum, I hope they will pause to wonder why Americans remain so bitterly divided today when there is so much shared and inspiring history to unite us.