We banked out over the Gulf of Bahrain and made a long, left-hand swing onto our easterly course. It would have been a whole hell of a lot quicker to head directly northeast across the gulf. But that would have taken us over the dubious southern uplands of the Islamic Republic of Iran, and we do not do that.

Instead we stayed south, flying high over the friendly coastal deserts of the United Arab Emirates, north of the burning sands of the Rub al Khali, the Empty Quarter. Astern of us lay the fevered cauldrons of loathing in Iraq and nearby Kuwait, places where I had previously served. Below us were the more friendly, enlightened desert kingdoms of the world’s coming natural-gas capital, Qatar; the oil-sodden emirate of Abu Dhabi; the gleaming modern high-rises of Dubai; and then, farther east, the craggy coastline of Oman.

None of us were especially sad to leave Bahrain, which was the first place in the Middle East where oil was discovered. It had its history, and we often had fun in the local markets bargaining with local merchants for everything. But we never felt at home there, and somehow as we climbed into the dark skies, we felt we were leaving behind all that was god-awful in the northern reaches of the gulf and embarking on a brand-new mission, one that we understood.

In Baghdad we were up against an enemy we often could not see and were obliged to get out there and find. And when we found him, we scarcely knew who he was — al Qaeda or Taliban, Shiite or Sunni, Iraqi or foreign, a freedom fighter for Saddam or an insurgent fighting for some kind of a different god from our own, a god who somehow sanctioned murder of innocent civilians, a god who’d effectively booted the Ten Commandments over the touchline and out of play.

They were ever present, ever dangerous, giving us a clear pattern of total confusion, if you know what I mean. Somehow, shifting positions in the big Hercules freighter, we were leaving behind a place which was systematically tearing itself apart and heading for a place full of wild mountain men who were hell-bent on tearing us apart.

Afghanistan. This was very different. Those mountains up in the northeast, the western end of the mighty range of the Hindu Kush, were the very same mountains where the Taliban had sheltered the lunatics of al Qaeda, shielded the crazed followers of Osama bin Laden while they plotted the attacks on the World Trade Center in New York on 9/11.

This was where bin Laden’s fighters found a home training base. Let’s face it, al Qaeda means “the base,” and in return for the Saudi fanatic bin Laden’s money, the Taliban made it all possible. Right now these very same guys, the remnants of the Taliban and the last few tribal warriors of al Qaeda, were preparing to start over, trying to fight their way through the mountain passes, intent on setting up new training camps and military headquarters and, eventually, their own government in place of the democratically elected one.

They may not have been the precise same guys who planned 9/11. But they were most certainly their descendants, their heirs, their followers. They were part of the same crowd who knocked down the North and South towers in the Big Apple on the infamous Tuesday morning in 2001. And our coming task was to stop them, right there in those mountains, by whatever means necessary.

Thus far, those mountain men had been kicking some serious ass in their skirmishes with our military. Which was more or less why the brass had sent for us. When things get very rough, they usually send for us. That’s why the navy spends years training SEAL teams in Coronado, California, and Virginia Beach. Especially for times like these, when Uncle Sam’s velvet glove makes way for the iron fist of SPECWARCOM (that’s Special Forces Command).

And that was why all of us were here. Our mission may have been strategic, it may have been secret. However, one point was crystalline clear, at least to the six SEALs in that rumbling Hercules high above the Arabian desert. This was payback time for the World Trade Center. We were coming after the guys who did it. If not the actual guys, then their blood brothers, the lunatics who still wished us dead and might try it again. Same thing, right?

We knew what we were coming for. And we knew where we were going: right up there to the high peaks of the Hindu Kush, those same mountains where bin Laden might still be and where his new bands of disciples were still hiding. Somewhere.

The pure clarity of purpose was inspirational to us. Gone were the treacherous, dusty backstreets of Baghdad, where even children of three and four were taught to hate us. Dead ahead, in Afghanistan, awaited an ancient battleground where we could match our enemy, strength for strength, stealth for stealth, steel for steel.

This might be, perhaps, a little daunting for regular soldiers. But not for SEALs. And I can state with absolute certainty that all six of us were excited by the prospect, looking forward to doing our job out there in the open, confident of our ultimate success, sure of our training, experience, and judgment. You see, we’re invincible. That’s what they taught us. That’s what we believe.

It’s written right there in black and white in the official philosophy of the U.S. Navy SEAL, the last two paragraphs of which read:

We train for war and fight to win. I stand ready to bring the full spectrum of combat power to bear in order to achieve my mission and the goals established by my country. The execution of my duties will be swift and violent when required, yet guided by the very principles I serve to defend.

Brave men have fought and died building the proud tradition and feared reputation that I am bound to uphold. In the worst of conditions, the legacy of my teammates steadies my resolve and silently guides my every deed. I will not fail.

Each one of us had grown a beard in order to look more like Afghan fighters. It was important for us to appear nonmilitary, to not stand out in a crowd. Despite this, I can guarantee you that if three SEALs were put into a crowded airport, I would spot them all, just by their bearing, their confidence, their obvious discipline, the way they walk. I’m not saying anyone else could recognize them. But I most certainly could.

The guys who traveled from Bahrain with me were remarkably diverse, even by SEAL standards. There was SGT2 Matthew Gene Axelson, not yet thirty, a petty officer from California, married to Cindy, devoted to her and to his parents, Cordell and Donna, and to his brother, Jeff.

I always called him Axe, and I knew him well. My twin brother, Morgan, was his best friend. He’d been to our home in Texas, and he and I had been together for a long time in SEAL Delivery Vehicle Team 1, Alfa Platoon. He and Morgan were swim buddies together in SEAL training, went through Sniper School together.

Axe was a quiet man, six foot four, with piercing blue eyes and curly hair. He was smart and the best Trivial Pursuit player I ever saw. I loved talking to him because of how much he knew. He would come out with answers that would have defied the learning of a Harvard professor. Places, countries, their populations, principal industries.

In the teams, he was always professional. I never once saw him upset, and he always knew precisely what he was doing. He was just one of those guys. What was difficult and confusing for others was usually a piece of cake for him. In combat he was a supreme athlete, swift, violent, brutal if necessary. His family never knew that side of him. They saw only the calm, cheerful navy man who could undoubtedly have been a professional golfer, a guy who loved a laugh and a cold beer.

You could hardly meet a better person. He was an incredible man.

Then there was my best friend, Lieutenant Michael Patrick Murphy, also not yet thirty, an honors graduate from Penn State, a hockey player, accepted by several law schools before he turned the rudder hard over and changed course for the United States Navy. Mikey was an inveterate reader. His favorite book was Steven Pressfield’s Gates of Fire, the story of the immortal stand of the Spartans at Thermopylae.