The three gun batteries at North Head / Maungauika were:
- North Battery to defend the Rangitoto Channel
- South Battery to defend the inner harbour
- Summit/Cautley Battery on the top of the hill
These fortifications were upgraded and improved over 25 years by convict labour of up to 40 prisoners living in barracks on the hilltop. The prisoners added extensive tunnel systems, underground storerooms, and various observation posts. The armaments of the fort included gun pits, searchlights, and a remote-detonated minefield that stretched across to Bastion Point.
None of the guns at North Head / Maungauika were ever fired at an enemy. They were only fired for training or ceremonial purposes. One such occasion was a four-gun memorial salute for Queen Elizabeth II on her visit in 1953.
The disappearing guns
By 1900 North Head was well-defended with three 8-inch, 64-pounder Armstrong disappearing guns. When these guns were made in 1886, they were the most up-to-date weapons of their type available. The barrels alone weighed over 13 tons and they were designed to retract underground when fired—hence the name ‘disappearing gun’.
Once hidden in their pit the guns could be reloaded under cover before being returned to the surface for the next shot. One of the few remaining disappearing guns in the world can still be seen at South Battery. This is the gun shown on the cover of Mystery Under Maungauika.
By 1900, additional guns were installed at North Head, including the rifled muzzle loaders, two of which are currently on display in Albert Park. In 1905, two 6-inch Mark VII guns were brought over from England and served as the primary defence during World War I.
As technology advanced, ship guns became capable of firing over longer distances. This rendered the old fort at North Head / Maungauika too close to the city it was meant to defend. Consequently, new batteries were constructed at Motutapu, Castor Bay, Whangaparāoa, and Waiheke Island. North Head shifted its focus to becoming an administrative centre.
The 6-inch guns at North Head were relocated to Whangaparāoa, while two older 4-inch guns took their place in 1941. This battery was responsible for guarding the entrance to the harbour. During World War II, North Head also housed an anti-submarine boom, which consisted of a wire netting barrier and two guns at sea level. This protected the harbour from potential submarine attacks.
In 1950, the coastal defences at North Head / Maungauika were decommissioned. Only one of the disappearing guns remained behind. It was considered obsolete and proved too challenging for the scrap merchant who purchased it to disassemble and remove. After the departure of the army, the area was converted back into a reserve—but the New Zealand Navy kept a portion of the summit for their training school.