The United States Navy Africa Squadron, Brazil Squadron and the Home Squadron was assigned the task of intercepting the ships which were bringing Africans across the Atlantic Ocean to the slave markets where "black ivory" found numerous customers. Since the War for Independence had been costly, no American warships were constructed between 1783 and 1795. The Navy Department was created on 30 April 1798, four years after President George Washington had communicated with Congress and expressed his alarm at the outrageous behaviour of Algeria. On 27 March 1794, following communication with President Washington, Congress authorised the purchase or construction of six frigates. These ships included the first "Constellation", launched 7 September 1797 and "Constitution", a ship that would be briefly employed in the African Squadron. Few new ships were built in the United States after 1801 until "Guerriere" was launched on 20 June 1814. It proved to be an effective warship in the War with the Barbary Pirates in 1815.