Al-Qaida’s war against America did not begin on Sept. 11, 2001, with the terrorist attacks that left nearly 3,000 people dead.

America’s job of defending herself from terrorism did not end on May 1, 2011, when a small team of U.S. special forces killed al-Qaida leader Osama bin Laden in a mansion in Abbottabad, Pakistan.

But on this one day, justice was delivered — with one tactical strike, with the polar opposite of the indiscriminate attacks engineered by bin Laden and carried out by his like-minded zealots.

With one strike, lasting not even 40 minutes.

We cannot exaggerate its significance. In many respects, we can only imagine its importance.

What could this possibly mean for families who lost husbands and wives, mothers and fathers, daughters and sons, at the hands of al-Qaida’s senseless brutality? Bin Laden’s victims and targets were largely but not exclusively American: Such was the randomness, the madness, of his murderous ways.

What could it possibly mean to the soldiers — and to the families of fallen soldiers — who were dispatched to hostile lands for something we now call, in simplistic shorthand, a war on terror?

What could it mean to the nation’s current commander in chief? And to his immediate predecessor? The search for bin Laden, spanning two presidencies, transcends political party — that most uncommon objective, in times of turbulence, that truly unites our United States.

Bin Laden sought to break us. He sought to divide us. But his legacy is one of carnage and cowardice. A manipulator of minds and a hijacker of the Muslim faith, he issued orders and videotaped statements from places of hiding. On Sunday, the front line found bin Laden. After months of planning, an elite group of U.S. sailors acted with what President Obama rightly called “extraordinary courage and capability.” U.S. forces struck with precision and emerged unscathed. Their bravery reflects and personifies their nation’s resolve.

Ultimately, this is a story of resolve.

The fact that it took nearly a decade to track down bin Laden should not go unnoticed by any of us; it illustrates that, by its nature, counterterrorism is a painstaking objective. But the fact that bin Laden was found sends a message to his followers and would-be successors.

Notice has been served.

Others will follow bin Laden’s diabolical doctrine. Our determination and our defenses will be tested. The death of bin Laden — “al-Qaida’s leader and symbol,” in Obama’s words — does not equate to al-Qaida’s demise.

Bin Laden’s death does not bring a conflict to conclusion, but it does provide a measure of closure. Two dates, Sept. 11, 2001, and May 1, 2011, will be forever linked in history. On one end of the continuum, a day of terror and tragedy. On the other end, a day of courage and valor.