At the outbreak of war in 1939, 12 signalmen from the Royal New Zealand Naval Volunteer Reserve landed on the island to man a Port War Signal Station near the lighthouse. 

If an enemy ship came into the harbour, the men would signal its presence to commanders operating gun emplacements on Whangaparaoa, Rangitoto, North Head and Waiheke Island.  

Following the bombing of Pearl Harbor (7 December 1941), the US poured money into New Zealand defences, and the Army established a Fortress Observation Post.

As well as alerting gunners in the surrounding area, Navy staff could activate mines – laid along the Tiri channel and out to Rakino Island –  by pressing a button onshore. The presence of submarines was detected by a loop cable that was laid over the channel.

The Navy staff were rotated regularly and life was largely without drama. One of the few Naval staff complaints concerned the Lighthouse Service’s old, stubborn horse which was used to ferry building supplies on site.

“This animal is not only vicious but obstinate to such a degree that no amount of persuasion or coercion by the entire personnel of the island will induce him to cover the additional half mile to the new PWSS…Approval is sought for the purchase of a more suitable horse at an estimated cost of £25.”