Since its official establishment, June 14, 1775 — more than a year before the Declaration of Independence — the U.S. Army has played a vital role in the growth and development of the American nation. Drawing on both long-standing militia traditions and recently introduced professional standards, it won the new republic's independence in an arduous eight-year struggle against Great Britain. At times, the Army provided the lone symbol of nationhood around which patriots rallied. [Source: Army.mil]
They have create the events on the history of the Army that you may find interesting at the URL
http://www.army.mil/1775/timeline.html.
Happy 250th Birthday Army - May all who served and those serving today enjoy the day.