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.