The 3d U.S. Infantry Regiment, traditionally known as "The Old Guard," is the oldest active-duty infantry unit in the Army, serving our nation since 1784.The Old Guard is the Army's official ceremonial unit and escort to the president, and it also provides security for Washington, D.C., in times of national emergency or civil disturbance.The unit received its unique name from Gen. Winfield Scott during a victory parade at Mexico City in 1847 following its valorous performance in the Mexican War. Fifty campaign streamers attest to the 3d Infantry's long history of service, which spans from the Battle of Fallen Timbers to World War II and Vietnam.Since World War II, The Old Guard has served as the official Army Honor Guard and escort to the president. In that capacity, 3d Infantry soldiers are responsible for conducting military ceremonies at the White House, the Pentagon, national memorials and elsewhere in the nation's capital. In addition, soldiers of The Old Guard maintain a 24-hour vigil at the Tomb of the Unknowns, provide military funeral escorts at Arlington National Cemetery and participate in parades at Fort Myer and Fort Lesley J. McNair.The black-and-tan "buff strap" worn on the left shoulder by each member of the 3d Infantry is a replica of the knapsack strap used by 19th-century predecessors of the unit to display its distinctive colors and distinguish its members from other Army units. The present buff strap continues to signify an Old Guard soldier's pride in personal appearance and precision performance that has marked the unit for 200 years.A further distinction of The Old Guard is the time-honored custom of passing in-review with fixed bayonets at all parades. This practice, officially sanctioned by the War Department in 1922, dates to the Mexican War in 1847 when the 3d Infantry led a successful bayonet charge against the enemy at Cerro Gordo. Today, this distinction is still reserved for The Old Guard alone.