It was the third time ever the "disappearing gun", a British Armstrong 8-inch Mark VII cannon, perched atop Devonport's North Head Maunganuika, was fired, at just after 11am this morning. The cannon predates World War I and was mounted on top of the volcanic cone in the late 1800s out of fear of a Russian navy attack. The "disappearing gun" appeared and was loaded earlier in the morning, before the guests had arrived on the muddy hillside. The battery gun was designed to retract into the ground after firing in attempts to conceal its location, hence its nickname, the "disappearing gun". Gallagher said that, originally, the disappearing gun was supposed to be built as a part of a great defence system, but it didn't have the accuracy.

Source: Stuff July 03, 2017 03:22 UTC