The military guard at the Tomb of the Unknown Soldier is changed in an elaborate ceremony which happens every day at Arlington National Cemetery in Washington, D.C.
Twenty-four hours a day, soldiers from the 3rd U.S. Infantry Regiment, known as “The Old Guard,” stand watch over the Tomb.
The Tomb Guards, also called Sentinels, are chosen for this prestigious and highly selective post only after rigorous training and a demanding series of examinations.
The Old Guard has held this distinguished duty since 1948.
An impeccably uniformed relief commander appears on the plaza to announce the changing of the guard.
Soon, the new Sentinel leaves the Tomb Guard quarters and unlocks the bolt of his or her M-14 rifle, signaling to the relief commander to begin the ceremony.
The relief commander walks out to the Tomb and salutes, then faces the spectators and asks them to stand and remain silent during the ceremony.
The relief commander conducts a detailed white-glove inspection of the weapon, checking each part of the rifle once.
Then, the relief commander and the relieving Sentinel meet the retiring Sentinel at the center of the black mat in front of the Tomb.
All three salute the Unknown Soldiers who have symbolically been given the Medal of Honor.
The relief commander orders the relieved Sentinel, “Pass on your orders.”
The current Sentinel commands, “Post and orders, remain as directed.”
The newly posted Sentinel replies, “Orders acknowledged,” and steps into position on the mat.
When the relief commander passes, the new Sentinel begins walking at a cadence of 90 steps per minute.
The Tomb Guard marches exactly 21 steps down the black mat behind the Tomb, turns, faces east for 21 seconds, turns and faces north for 21 seconds, then takes 21 steps down the mat and repeats the process.
Next, the Sentinel executes a sharp “shoulder-arms” movement to place the weapon on the shoulder closest to the visitors, signifying that he or she stands between the Tomb and any possible threat.
WATCH: Jim on History, Changing Of The Guard