This tradition of honor, known as Flags-in, has taken place ever since 1948 when The Old Guard was appointed as the ceremonial unit for the U.S. Army. During the Memorial Day weekend, members of The Old Guard patrol the cemetery to make sure each gravesite remains decorated and honored with a flag. In addition, sentinels for the Tomb of the Unknowns place flags at each of the unknown servicemen graves.
The flags are removed after the three-day Memorial Day weekend.
More about Arlington National Cemetery
More about the 3rd United States Infantry Regiment - The Old Guard
More about Memorial Day Weekend Events in the Southeast
Flags-in Information Source: Arlington National Cemetery


