The Royal Engineer Officers, Major General Sir William Jervois and Lieutenant Colonel Peter Scratchley, published their report in 1877. This report provided the basis for coastal defence for the next thirty years in New Zealand and Australia.
The original coastal defence battery in Warrnambool was earthen emplacement for Smooth Bore gun on Cannon Hill, about one Kilometre west of the new battery at Flagstaff Hill. This site has now been lost.
Warrnambool Battery, also known as Warrnambool Garrison and Flagstaff Hill, was a new site built as part of a wider state upgrade in coastal defences.
The two 80-pdr RML guns were part of a consignment of twenty-six guns sent to Australia in December 1866. These two guns were mounted in the new fortification during 1887. The original wooden carriages, which can be seen on site, were replaced by iron garrison carriages in 1888.
In 1895 a 5-inch BL gun on an HP mounting was installed between the two existing 80-pdr RML gun emplacements. This gun remained operational until 1904. Two mobile 4.7-inch naval guns where then used to arm the battery.
This was one of three batteries of two 68-pdr RML and then 80-pdr RML guns built in this area in the 1880s. The other batteries were Portland Battery and Port Fairy Battery.
A brief summary of the Warrnambool, Port Fairy and Portland Batteries and volunteer units serving them, prepared by David McGinness, can be downloaded here.