The 51st Battalion, Far North Queensland Regiment is an Australian Army Reserve Regional Force Surveillance Unit headquartered at Porton Barracks in Cairns. The battalion's primary role is to conduct reconnaissance and surveillance tasks in support of border security operations. Its area of operations includes the Torres Strait and the Cape York littoral environment. Additional tasks for 51FNQR include the collection and collation of military geographic information as well as community engagement and disaster relief operations.

The Australian Army Reserve is a collective name given to the reserve units of the Australian Army. Since the Federation of Australia in 1901, the reserve military force has been known by many names, including the Citizens Forces, the Citizen Military Forces, the Militia and, unofficially, the Australian Military Forces. In 1980, however, the current name—Australian Army Reserve—was officially adopted, and it now consists of a number of components based around the level of commitment and training obligation that its members are required to meet.