A new and revolutionary form of naval warfare was introduced in the era of the Ultra-Battleships for shore bombardment and also for naval combat, trying to complement the big calibre guns, howitzers and mortars.
The North-Pole Conglomerate engineers soon realized that ultra-big caliber artillery pieces (1,000 to 2,000 mm) had very low rate of fire as to maintain a moving enemy ship as a target, making a direct impact by chance. This is a non-practical proposition given the cost of each artillery shoot and of the whole ship in campaign.
The idea behind a the cruise missile is simple, but the mechanical behind is complex. Cruise missiles are V.T.O.L. aerial machines that fly guided to his target by a programming path, and stabilized by a gyroscope. To hit a moving target, is needed instead some sort of terminal guidance, by wire or by radio signals. The fly can be monitored from a high post in the ship or even from a manned aircraft that fly near the target.
South-Pole floating islands engineers have developped the Ecuatorial Fortresses long time ago, but recently have deployed new weapons inside the main concrete towers. They mastered the salvo-shooting of a kind of multi-tube mortars capable of fire, in rapid sucession, six 1,200mm calibre, 5,000 Kg armor-piercing projectiles against the North-Pole Conglomerate Ultra-Battleships.
Even more recently, it is said that they are employing a new multiple device of rocket nature, so the weapon dispenses with the recoil and also can be reloaded quickly. It is a multiple rocket launcher with five or six tubes that launch spin-stabilized projectiles of 2,000mm diameter and 12,000 Kg in launching weight to 15 Km maximum range.
In this picture, the missile is represented with transparent covers as to show the internals. The big yellow spiral is the tank for solid fuel that is consumed during cruise flight, generating the gas enough for a 60% of maximum thrust. Inside it is the shorter lenght blue spiral that houses the solid fuel consumed during ascend flight, reaching 100% power in the gas turbine. Also visible is the starter solid fuel tank. All fuel is ignited by a separate pyrotechnical device at the right time.
NOTE: in this polarized oceanic world that I imagine, only vertical take-off and landing aircraft exist. These machines are propelled by rotating wings. No other form of aerial flying is know or is allowed by strictly-observed War Laws, except artillery projectiles.