<Li> Marches 21 steps south down the black mat laid across the Tomb . </Li> <Li> Turns and faces east, toward the Tomb, for 21 seconds . </Li> <Li> Turns and faces north, changes weapon to outside shoulder, and waits 21 seconds . </Li> <Li> Marches 21 steps down the mat . </Li>

When was the last time the tomb of the unknown soldier was unguarded