Which country scared New Zealand so much, that it was made to construct the coastal fortifications?

In the 1870s New Zealand was a young self-governing colony of Britain. It had developed no coastal defences of any consequence and was becoming increasingly sensitive to how vulnerable its harbours were to attack by a hostile power or opportunistic raider.

(In 1873 an Auckland editor perpetrated) ...what has been hailed the greatest spoof in the country's history. The Monday, 18 February 1873 edition of the Southern Cross reported the sudden declaration of war between England and Russia. As a result, the Russian warship Kaskowiski – whose very name should have made sober readers suspicious – had allegedly entered Auckland Harbour on the previous Saturday night and proceeded to capture a British ship, along with the city's arms and ammunition supply, and hold a number of leading citizens for ransom. The 954-man Russian vessel obviously meant business, with a dozen 30-ton guns as well as a remarkably new advance in warfare, a paralysing and deadly "water-gas" that could be injected into enemy ships from a great distance.

The Southern Cross article created panic and the Government commissioned its first reports on the colony's defences. Then Russia declared war on Turkey in 1877 producing another "scare". The decision was taken to construct fortifications and purchase naval boats which would protect the harbours. By 1885 work started in earnest on the construction of what eventually became seventeen forts, further encouraged by yet another Russian scare.