The 66th Congress passed Public Resolution #67 to construct a tomb at Arlington Cemetery for an unknown soldier killed in France. This soldier represented all of the unknown soldiers killed in WWI.
The Tomb has been under 24 hr guard since July 2, 1937 under the sole responsibility of the 3rd US Infantry.
The shoes worn by the Sentinals are built up so the heel and sole are equal in height, allowing the sentinel to stand with a perfectly straight back and to walk in a fluid movement, meaning the bayonet does not “bob” up and down in each step.
The walk is 21 steps, then a 21 second pause facing the tomb, then changing the bayonet to the other shoulder, followed by another 21 second pause, which alludes to the 21 Gun Salute, the highest honor given to any military or dignitary.