British settlement of Australia began as a penal colony governed by a captain of the Royal Navy. Until the 1850s, when local forces began to be recruited, British regular troops garrisoned the colonies with little local assistance. From 1788 marines guarded English settlements at Sydney Cove and Norfolk Island; they were relieved in 1790 by a unit specifically recruited for colonial service, and in 1810 the 73rd Regiment of Foot became the first line regiment to serve in Australia. From then until 1870, 25 British infantry regiments and several smaller artillery and engineer units were stationed in the colonies. One role of the troops was to guard Australia against external attack, but their main job was to maintain civil order, particularly against the threat of convict uprisings, and to suppress the resistance of the Aboriginal population to British settlement.