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"Depend upon it, sir, when a man knows he is to be hanged in a fortnight, it concentrates his mind wonderfully," said Samuel Johnson.

And as it is with men, so it is with nations.

Monday, Dr. Deborah Birx, White House coronavirus response coordinator, projected some 100,000 to 200,000 U.S. deaths from the pandemic, "if we do things almost perfectly." She agreed with Dr. Anthony Fauci's estimate that, if we do "nothing," the American dead could reach 2.2 million.

That 2 million figure would be twice as many dead as have perished in all our wars from the American Revolution to the Civil War, World War I and II, and Korea and Vietnam.

This does indeed concentrate the mind wonderfully.

Now add to this slaughter of our countrymen a market plunge steeper than the 1929 Crash and a 1930s-style Depression. Wall Street analysts are talking of a wipeout of 30% of our GDP and unemployment reaching 35%.

What a difference a month can make.

On March 3, Super Tuesday, we were caught up in the 14 primary contests after Joe Biden's stunning victory in South Carolina, which broke the momentum of Sen. Bernie Sanders' wins in Iowa, New Hampshire and Nevada.

What March 2020 produced and what it appears to portend is a sea change in U.S. history, an inflection point, an event after which things never return to what they were.

The coronavirus crisis seems to be one of those epochal events that alter the character of the country and the course of the republic.

Consider what has happened in three weeks.

The Republican Party, the party of small government and balanced budgets, approved with but a single dissent a $2 trillion emergency bill. There is talk now of a second $2 trillion bill, this one for infrastructure.

In a single month then, a Republican Senate and president grew the federal budget by 50% and are looking to double that.

For years, Democrats raised alarms about Trump's poaching of the powers of the other branches. Now Democrats are demanding to know why Trump has not shut down the economy by presidential decree and not used his latent dictatorial powers to order U.S. companies to produce what the nation's hospitals demand.

Democrats who long accused Trump of xenophobia and racism for seeking to close the borders to migrants entering the country illegally are now silent as Trump closes America to the world.

First Amendment free press champions are calling for Trump's White House briefings not to be carried on TV because the president is spouting propaganda and lies. The problem: The people are watching and approving of what the media think the people ought not see.

If people in a crisis will jettison lifelong beliefs like this readily, how enduring will their professed belief in democracy itself prove?

The president thinks this will be a V-shaped recession, that once the economy hits bottom and turns up, it will soar, as in 1946 when pent-up demand from World War II was unleashed and America began to churn out cars and consumer good as rapidly as it had weapons of war.

Perhaps. But put me down as a skeptic. You can't go home again. The shattering events of March, followed by what is coming in April and May, will have lasting impacts on the hearts and minds of this generation.

That once-insatiable appetite for Chinese-made goods at the mall -- will it really return? Will Americans, after having "socially distanced" for months from family and friends, be reassured of their safety and pack into restaurants in July?

Observing the carrier Theodore Roosevelt in Guam offloading scores of sailors infected with coronavirus, will Americans be up for a clash with a China that is even today asserting its claims to the South China Sea?

Will Americans who survive this crisis care whether Iranian-backed Shiites dominate Iraq or Saudi-backed Sunni prevail in Yemen?

If March shocked this nation as severely as 9/11, what is coming may be even more sobering.

Are millions of unemployed workers without the cash to pay for or to find medicine and groceries likely to stay indoors for weeks or months?

All those criminals being given early release from virus-infested jails and prisons without the means to provide for themselves and their families, how will they react to weeks of mandatory sheltering in place?

Will MS-13 and its thousands of members, and its rival gangs that live off narcotics sales, comply?

Americans have done well in staying home in March. Will they do so through April, May and perhaps June? Or will the system gradually break down just as the second wave of the virus in the fall appears?

In times of crisis in America, there is a tradition of self-sacrifice.

But there have also almost always been not a few whose mindset is that of the Fort Lauderdale spring-breakers.

Patrick J. Buchanan is the author of "Nixon's White House Wars: The Battles That Made and Broke a President and Divided America Forever."