It’s a solemn ceremony choreographed with the precision of an atomic clock, executed by a regiment of warm-blooded machines, and directed with the authority of a no-nonsense commander who only knows perfection. It’s a six-minute pas de trois that happens every hour on the hour during fall, winter, and night, and every half-hour during spring and summer–regardless of the weather or challenging conditions. And it’s a sacrament that’s never stopped since 1937.

The changing of the guard in front of the Tomb of the Unknown Soldier at Arlington National Cemetery is carried out with the pomp and circumstance of a Shakespearean ceremony, yet with the reverence of a canonization.

The rigorous training and commitment of the corps serving the monument is legendary. They are the best of an elite color guard from the 3rd Infantry Regiment, also known as The Old Guard, the nation’s oldest fighting force, serving since 1764.

The highly-selective unit is composed of impeccably dressed volunteers of similar stature, in peak physical condition, and with unblemished military records.

As if marching to a metronome that only he can hear, the sentinel paces to the south, rolling his feet effortlessly along a catwalk of worn rubber,

His gait and silent cadence is measured and precise…19…20…and 21 steps, a broad leg sweep, and CLACK, his heels lock with the force of two magnets attracted to each other. He quarter-turns sharply to the east, and whip-snap, CLACK, his heels lock again.

One Mississippi, two Mississippi…until he reaches 21, and his feet quarter-turn north, and CLACK, his shoes revealing the effort from hours of spit-polishing only achieved through tubs of Kiwi and micro-sanding.

He executes a sharp shoulder-arms, repositioning his sparkling M-14 from his right shoulder to his left, as if popping with his prop–his weapon always closest to the visitors to signify that the sentinel always stands between the Tomb and any possible threat.

After another 21 seconds of silence, the sentinel returns 21 steps north…

and CLACK, quarter-turn, CLACK, quarter-turn, CLACK. Shoulder-arms, one Mississippi, two Mississippi…always counting, always focused, no matter the distraction.

The significance of number 21 corresponds to a 21-gun salute, the highest military honor posthumously bestowed upon any service personnel.

A crowd of spectators has lined the marble steps outside the Memorial Amphitheater in eager anticipation of the one-o’clock ritual.

The hour tolls, and the sentinel on duty stands motionless, but at the ready.

From the opposite end of the plaza, the regiment commander appears beside the runway, and CLACK. In this ritual variation, the count-up to 21 continues, and marching resumes until the two honor guards pass.

Upon the commander’s return, he pivots to face the crowd of visitors:

Ladies and Gentlemen, may I have your attention, please. I am Sgt. Davenport of the 3rd Infantry Regiment, United States Army, Guard of Honor, Tomb of the Unknown Soldier. This ceremony which you are about to witness is The Changing of the Guard. In keeping with the dignity of this ceremony, it is requested of everyone to remain silent and standing. Thank you.

Meanwhile, on the south side of the plaza, the relief-sentinel stands at attention and awaits formal inspection from the commander–now marching past the on-duty sentinel.

After a graceful, yet deliberate weapons and uniform check from head to toe…

undertaken with the scrutiny of a dermatologist examining for basal cells…the relief-sentinel is deemed mission-ready.

They parade across the plaza in lock-step…

where they take up new positions in front of the shrine…

When the on-duty sentinel is officially relieved…

the new sentinel’s patrol resumes for the remaining hour.

However, on this particular day, at this particular hour, we were also witness to a wreath dedication ceremony from a local high school marching band…

which only added to an already moving tribute and ceremony.

But there was one last vital piece of business remaining before our day was done: an obligatory visit to the gravesite of JFK to pay my respects.

When John F. Kennedy was assassinated on Friday, November 22, 1963–the day before my 11th birthday–the announcement by Principal Simon came over the PA system, interrupting my Happy Birthday-song tribute. Immediately, the class went from cheers to tears in an instant, like a bipolar meltdown.

The pervasive sadness swept my home that evening, and I can’t remember when the sadness lifted. There was nothing any of us could do to keep from crying.

My 11th birthday was a turning point in my life–one of those moments where it’s impossible to forget where you were or what you were doing when you learned of something so profound, or horrific, or cataclysmic that you knew right then and there that your life had changed forever.

And while there’s no going back to a wrinkle in time, processing the tragedy is always hard to reconcile, even after all these years, as is wondering about the wonder that might have been.

The Sentinel’s Creed

My dedication to this sacred duty is total and wholehearted.
In the responsibility bestowed on me, never will I falter.
And with dignity and perseverance.
My standard will remain
Through the years of diligence
And the discomfort of the elements,
I will walk my tour in humble reverence to the best of my ability.
It is he who commands the respect I protect,
his bravery that made us so proud.
Surrounded by well-meaning crowds by day,
alone in the thoughtful peace of night,
this Soldier in honored glory rest under my eternal vigilance.

PBS has produced the following video which masterfully demonstrates the precision of the pageantry, and reflects the awe of the ceremony.