With this issue of THE BIG PICTURE, sound cameras cover military activities in the nation's capital. This might be called the visitors' view of Washington. Through the camera lens, viewers will see the most famous of all military units in Washington -- the 3rd Infantry Regiment, whose origins go all the way back to the Revolutionary War. Only hand-picked officers and men are to be found in the ranks of the Third. Activities such as the changing of the guard at the Tomb of the Unknown Soldier will be shown. It is a simple ceremony, and yet an impressive one. Ceremonial color guards will be seen and interviewed at historic Mount Vernon. The story of the famed caparison horses at Fort Myer will be told. But not all the troops in the Washington area are for show and ceremony. Many fill jobs vital to the defense of the city and THE BIG PICTURE camera moves to the surrounding suburbs to show the anti-aircraft batteries. Following an alert, the cameras catch the men going into actions on the guns, the tankers of the 3rd Infantry rolling past the Pentagon, and the men of the 2nd Battalion moving to strategic positions as designated in Plan Able.