hull returned the ship's hull form to the range, speed, and stability of the original design performance as specified. However, the continuing advances of larger caliber guns, greater muzzle velocities, more accurate fire at longer ranges, and more energetic explosive fills of the shells demanded drastic improvements in armor protection. Some means had to be found to integrate armor protection into the total design of the warship at its inception. The rational application of armor had to achieve the most efficient use of the hull's displacement to provide buoyancy to the deadweight of the ship's armor. "All or nothing" was the design solution. The "all-or-nothing" philosophy of armor design required the complete rethinking of battleship design, armor systems and the integration of the ship's design architecture with the armor protection system. With the rethinking of design, naval architects had to examine every system and function of a warship, and determine the functions and systems that were critical. The systems were assessed as to priority, relationships, and location within the hull and superstructure. The design was intended to ensure that battleships could (a) survive against the heaviest armor-piercing shells in use in the early part of the 20th century, (b) be able to carry powerful armament, and (c) retain useful speed and endurance. That was made possible by dispensing with the large areas of relatively light armor used in previous battleship designs. The weight saved was used to strengthen the armor protecting the vital areas of the ship, centralized within a compact space. The logic of the design was simple: if the ship were hit in vital areas (the ammunition and propellant magazines; the propulsion plant; the fire-control, command and communications sections), her survival was in jeopardy. On the other hand, if the ship were hit in non-vital areas (non-explosive stores, crew berthing and rest areas, offices and administrative areas), it would most likely not result in the ship's destruction. The armor also strengthened the hull. In the ideal form of the system, all of a battleship's armor is concentrated to form an armored "citadel" around the ship's magazine spaces. The citadel is an armoured box of uniform thickness designed to defend against the largest enemy guns. The propulsion plant, communications systems, weapons, ammunition stores, and command and control of the ship were located in a single area within and beneath the armored citadel. By stripping away the armor from all