I bought a book at Arlington called "In Honored Glory". I would recommend it to anyone interested in history and particularly in the cemetery. This is what is written about the Tomb Guard ...
The three Unknown Servicemen are under a 24-hour honor guard, which was established in 1937. The 3rd United States Infantry, "The Old Guard," assumed the duty of protecting the Tomb in 1948. There are three reliefs of sentinels assigned to the Tomb. The soldiers are generally recruited from Fort Myer, Virginia, and must possess both an outstanding military record and an intense desire to become a member of the elite Tomb Guard. Likewise, all must meet the minimum five-foot ten-inch height requirement.
(I talked to the Sergeant of the Guard out front and asked him about some of the requirements ... it is actually between 5' 11" and 6' 4" with a waist no larger than 29 inches!! 29 inches??!! 
)Prospective sentinels first interview with the Sergeant of the Guard and the individual Relief Commander. If deemed acceptable, the soldier is assigned for a two-week probationary period of temporary duty (TDY) where he is introduced to the numerous required duties. Once assigned to Company E (the Tomb Guard), the "New Man" must continue his intense and rigorous training and is expected to work continually to perfect his uniform, to assist the other sentinels in preparing for their 'walks,' and to learn the history of Arlington Cemetery.
For the next several weeks, the "New Man" is trained by members of his relief in the "catacombs" located under the colonnade area of the Amphitheater. Initially, the soldier is permitted only low visibility walks, a two-hour shift after the cemetery is closed to public visitation and at a time when the Tomb is a restricted military area. Once deemed proficient, he is finally allowed to enter the relief's rotation and is permitted to guard the Tomb on a regularly scheduled basis throughout the day and night.
After nine months of duty, the "New Man" is given a battery of tests. His uniform and walk are carefully scrutinized by other relief commanders and he is evaluated on his cemetery and military knowledge. Once deemed proficient, the soldier is award the Tomb Guard Badge, a silver award which consists of an engraving of the Tomb, an inverted craven wreath, and the words "Honor Guard."”The badge is prominently displayed on the right breast pocket of the soldier’s uniform. After 12 months of honorable service at the Tomb, the "Badge Holder" is given permanent orders for the decoration and may then wear the Tomb Guard Badge for the duration of his military career, regardless of subsequent rank or branch of the service. Since its inception in 1958, less than 600 sentinels have successfully received permanent orders for the Tomb Guard Badge including Sgt. Heather Johnsen, the first female sentinel, who earned her badge in 1996.
The soldiers at the Tomb are authorized three different uniforms - a blouse, an overcoat, and a raincoat. All are maintained by the individual soldier who must remove and polish all bass and insignia daily to the rigorous standards demanded by the relief commanders. The blouse is made of wool and is worn year-round despite the legendary heat of Washington summers; it is the only fabric that will adequately hold a crease in hot weather. The overcoat is worn only when temperatures are below 45 degrees and the raincoat during periods of inclement weather.
(According the Sergeant, the Guards routinely start preparing their uniforms and dress at 4 am - EVERY DAY! And if it is not absolutely perfect, they cannot go out on the 'walk' until it is!)The uniforms, despite public perception, are not tailored; to give the uniform a smooth appearance, all excess material is carefully tucked into the mandatory 29-inch waist belt by assisting sentinels prior to the Guard Change. All the uniforms are dress Army blues reminiscent of the Continental regalia work by federal troops during the Civil War.
Each soldier is issued a pair of sunglasses for use while guarding the Tomb. Although not considered a traditional part of the regulation military uniform, the sentinels are given a dispensation to wear the glasses since the bright, white marble can induce sun blindness and hinder their mission. The shoes worn by the sentinels are standard Army issue but additional layers of soles have been added to protect the soldiers'’feet from heat and cold.
(Also added is the side 'clackers' that make that loud click when they snap-to.)The black mat on the plaza in front of the crypt area is 63 feet long and is replaced each Memorial Day. The sentinel on duty takes 21 steps across the mat, turns, and faces the Tomb for 21 seconds, representative of the highest military tribute - the 21-gun salute.
The Tomb Guard carries an M-14 rifle which is currently issued only to the members of the 3rd Infantry and to selected sharpshooter regiments. The weapon weighs 9.5 pounds and is equipped with a chrome, ceremonial bayonet and a black mourning strap. The rifle is always maintained in a position between the visitors and the Tomb, indicating the soldiers' primary mission of protecting the shrine from intruders.
Each relief is on a three-day duty rotation, 24 hours on and 48 hours off.
(According to the Sergeant, it is now 24 on, 24 off, 24 on, 48 off, 24 on - I think that’s what he said - I know it’s a bit different than what was written.) During the off hours, however, the soldiers are expected to practice continually, to prepare their uniforms, and to enhance their knowledge of the cemetery, all the while maintaining standard military skill and combat readiness. During the daylight hours, the Change of the Guard ceremony occurs on the hour in the winter months and on a 30-minute schedule during the summer. At night, the sentinel is on duty for a two-hour shift and is permitted to wear his regular army greens
(camo). The Guard can sling arms and conduct a perimeter walk around the plaza area but must make a traditional pass along the mat at regular intervals.
According to the Sergeant, the Guard is under constant scrutiny by an NCO in the catacombs by way of two cameras. The NCO is watching for any unauthorized movement or untoward happenings with the walking Guard. If he does something not 'allowed' he is called to task after his tour is finished and given extra instruction on proper bearing and procedure.) The origin of the ceremonial change is obscure. Inspections tended to vary with the personalities of the individual sergeants but are now a standardized procedure with only minor variations permitted. The inspection is genuine. If a sentinel is deemed deficient, he will be ordered by the sergeant back to the quarters to make any necessary uniform corrections. The rifle is also checked for cleanliness by the sergeant who is careful to soak his white cotton gloves with water prior to the inspection to ensure an adequate grip.
(I asked about what happens if the Guard is deficient at inspection and Sergeant told me unless it is HUGELY apparent, the Guard is allowed to walk, but is reprimanded and goes through some 'extra training' after his shift is done. If anyone drops the rifle he is DONE with Tomb Guard duty and his name is removed from the Guard Wall with a "Revoked" sign replacing it.)Duty at the Tomb is voluntary and sentinels may leave to return to the company at any time. Most, however, choose to remain between 12 and 18 months and view their tour at Arlington as the highlight of their military careers.
(Sergeant said most do 18 months then ask for extensions and some have been on Tomb rotation for over 3 years!) Indeed, the sentinels believe their duty is a small tribute compared to the ultimate sacrifice offered by the Unknowns who lost their lives to protect the ideals of the nation. Their belief is reflected in the Sentinels' Creed which is memorized by all of the Guards and which encapsulates their feelings:
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 perfection.
Through the years of diligence and praise
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 will in honored Glory rest
Under my eternal vigilance.
Training takes about a full year and is totally voluntary. The Guard has to WANT to do it and it is a rigorous tour - all kinds of weather, year-round, and to be held to a standard of the highest perfection. Not all make it thru the training. It is an awesome sight to watch, isn't it? Gotta feel proud of those boys that do it (no women on Tomb Guard right now).
It is soooo beautiful!!!