On 30 April,1798 Congress establishes the Department of the Navy as a separate cabinet department. Previously, naval matters were under the cognizance of the War Department. (I like the name War Department better then Department of Defense) Benjamin Stoddert is named as the first Secretary of the Navy.
United States Navy claims 13 October 1775 as the date of its official establishment, when the Second Continental Congress passed a resolution creating the Continental Navy. But with the end of the American Revolutionary War, the Continental Navy was disbanded. Then with threats to American merchant shipping by Barbary pirates from four North African States, in the Mediterranean, President George Washington signed the Naval Act of 1794 the act authorizing the construction of the Navy’s first six frigates ? Congress passed a resolution to establish with haste a national navy that could protect U.S. commercial vessels from attacks by Barbary pirates in the Mediterranean and nearby Atlantic waters. The Algerian and Tunisian pirates joined forces, and by 1650 more than 30,000 of their captives were imprisoned in Algiers alone. Piracy was the cause of several wars between Tripolitania and the United States in the 19th century.