The British General Staff's battle map.

Last month the New York City Council approved a developer’s proposal to erect an 18-story apartment tower on the East River in Brooklyn, just east of the Brooklyn Bridge. The project is controversial not only because it would mar the view of the great bridge, but also because it would occupy one of the most significant sites in American history.

The site is little known; it marks a retreat.

At this very point on the night of Aug. 29, 1776, and during the foggy early morning hours of the next day, Gen. George Washington quietly evacuated 9,000 troops — most of his newly formed Continental Army — across the river to Manhattan, escaping to fight another day.

The army had been badly mauled by the British in the Battle of Brooklyn and was almost surrounded. Had winds not been against them, British warships in the New York harbor would have sailed up this tidal estuary to close the trap. Washington and his army would have been captured, almost before the ink was dry on the Declaration of Independence whose signing we celebrate this weekend.

Washington and his commanders might well have been hanged, along with the signers of the Declaration. History tells us they were aware of the risk; as Benjamin Franklin may or may not have told his fellow signers, “We must all hang together or most assuredly we will all hang separately.”

Great undertakings require great risk and demand much sacrifice. And sometimes a retrenchment. It’s a lesson that has been muddied over the last 233 years.

It should be recalled that even members of the “Greatest Generation” that fought and won World War II put such sacrifice off as long as they could. Similarly, we knew of the atrocities of the Taliban in Afghanistan and the threat posed by al-Qaida long before Sept. 11, 2001. As early as 2003, Warren Buffett was warning that trading in financial derivatives was a “time bomb” ticking under the economy.

Americans are an optimistic people, an admirable trait. Why sacrifice if you don’t have to? But when that optimism obscures a hard-eyed view of reality, catastrophe may await. Consider the following:

• Ten days ago, 212 members of the U.S. House of Representatives voted against the American Clean Energy and Security Act of 2009, the so-called “cap-and-trade” bill that aims to cut the nation’s production of greenhouse gases by 17 percent in the next 10 years and 83 percent by 2050. Global warming is a reality; no amount of industry-funded studies to the contrary (“Sunspots!”) can overcome that reality. Fixing it, if that’s still possible, will require significant financial and lifestyle sacrifices.
• President Barack Obama’s health care reform bill also portends great cost and sacrifice to many Americans. Insurance and drug companies worry about the loss of business. Doctors worry about the loss of income. Taxpayers worry about the cost, never mind that the cost of doing nothing may be even higher.
• Last month the Congressional Budget Office released a long-term forecast that says “the federal budget is on an unsustainable path — meaning that the federal debt will continue to grow much faster than the economy over the long run.” The CBO says that at current tax and spending rates, in 14 years the national debt will be bigger than the entire American economy. Ninety percent of the increase can be atrributed to rising spending on Medicare and Medicaid. Much of the rest can be laid at the feet of rising costs for Social Security.

Mr. Obama has been accused of taking on too many problems at the same time. Circumstances forced him to first address the collapse of the financial markets. Along with keeping the nation secure, that might have been enough for any president.

But Mr. Obama chose to move on global warming and health care reform because he recognizes that neither can wait. Both are existential threats to the American way of life.

He has chosen to try to fund them on a “pay-as-you-go” basis, realizing that putting them on the national credit card — as his predecessor did with the Iraq war and the Medicaid prescription drug plan — is not an option. The CBO says that the federal budget will be $9.3 trillion in the red over the next 10 years.

The nation can’t keep borrowing from future economic growth to pay for things it needs today. Given last week’s troubling unemployment numbers, it may need another jolt of stimulus spending, ideally for infrastructure projects that will last 30 years.

Borrowing to keep a car running so you can keep a job is one thing. Borrowing for groceries and gasoline is quite another, unless you can be sure your income is going to keep growing faster than interest costs.

America is devoting ever more of its future income to interest on debt for what it consumes today, borrowing from foreign governments, most notably China’s. At some point U.S. Treasuries stop looking secure.

The result: More recession, inflation and unemployment, even as baby boomers become eligible for Medicare and Social Security, increasing the demand for more spending and driving more debt and God help any politician who votes to decrease benefits.

Americans, including too many of their leaders in Congress, are refusing to accept reality in many forms: global warming, the unsustainability and unfairness of the existing health care system, the notion that we can buy weapons and highways and bridges we don’t need instead of investing in military and transit programs we do, the end of an era of excess.

Pull any of these strings and you find someone’s self interest at the end: members worried about re-election; industry and business worried about profit; constituents worried about their favorite federal program. Nobody wants to hear about sacrifice for the common good. Nobody wants to hear about retrenchment.

It may be that America now is dominated by what the Brits call the “I’m all right, Jack” philosophy: I’ve got mine, and that’s what matters.

It may be that our political system, fueled as it is by huge campaign contributions and lobbying from special interests, no longer is capable of enacting laws for the common good. The climate change bill, after all, passed only after dozens of breaks were inserted for special interests. The health care reform debate is dominated by the effect it would have on doctors, private insurers and pharmaceutical companies.

Mr. Obama may have to make the same case to the country that Washington made to his army before the Battle of Brooklyn:

“The hour is fast approaching on which the honor and success of this army, and the safety of our bleeding country, depend.”