sentences:  South Head was recognised as an important site for the young colony and, as early as the first year of settlement, a signal gun from HMS "Sirius" was installed at South Head in order to indicate the arrival of any ships.The first permanent military presence on South Head commenced in 1871 with the development of Coastal artillery emplacements to defend the Port of Sydney.The first barracks, occupied by members of the NSW Artillery, were completed 19 March 1877.