After the war the Royal Navy was saddled with a large number of tired and now obsolete dreadnoughts, all construction on new capital ships had ceased during the war and there was no new ships designed since the Queen Elizabeth and R class dreadnoughts and even they were now lacking in some areas, the new 'all or nothing' armour scheme was seen as ideal and the older ships had been built with the idea of armouring as much of the hull which in battle proved useless against a heavy shell and just acted as a means of setting a shell fuse off. The all or nothing scheme focused on maximum armour where it mattered, over a ships vitals like its engines, magazines and turrets and no armour where it didn't matter, where hits could be absorbed and ignored. After the First World War the Royal Navy needed a new battleship to suppliment its existing ships and lead the way in new designs that would replace them and tenders were put out to design the best ship that could be built to put the RN at the top of the tree in terms of battleship design once more. *The N3 design viewed from the top, note that its nigh identical to the G3 design. This was done at the same time as the G3 type Battlecruiser design was finally settled on and the Navy's new battleship looked like its faster cousin in almost every respect, including turret layout and general design, save that the G3 had two funnels whilst the new N3 would have only one. The biggest difference between the two was that the N3 would be slightly shorter and more beamy as well as considerably slower, capable of 23 knots instead of the G3's formidable 32. The considerable weight saved on engines instead went into extra armour and bigger guns.  The layout and armour scheme of the planned N3 design. Firepower and armour In World War 1 under Admiral Fishers urgings the British had developed an 18 inch naval gun and indeed fitted it on the most inappropriate ship for it, a huge, lightly built 'cruiser' the HMS Furious. Test firings were a source of woe as the blast of the heavy gun combined with the recoil and the Furious' light build saw her damaging herself with each firing, crew reported it 'raining' bolts inside the ship when they sheered off when the gun fired. Later removed and mounted on a monitor the General Wolfe the guns proved to be reliable and accurate and the effect of their 3300lb shell on targets can only be imagined. With this eventual success in mind the RN opted for an improved, longer barrelled version of the 18 inch gun for the N3 design giving her a 9 gun broadside totalling a staggering 29880lb broadside which would have dwarfed any other ship in service. HMS Furious with her single 18inch Mk-1 gun. Like the G3 the N3 was to have six dual turrets armed with 6 inch guns, three per side, six 4.7 inch high angle AA guns and four 10 barrelled 2lber pom-pom's laid out in exactly the same positions as the G3s, with the secondary armament aft and the main turrets grouped together forwards to shorten the armoured belt and save weight. They were also to be fitted with two sea planes launched from catapults in the sterm. What weight that didn't go into the added bulk of the 18 inch guns and their larger turrets and barbettes went into thickening the N3's armour scheme which followed the ideas and principles of the all or nothing scheme as well as having an internal angled belt to offer more resistance from plunging fire. The RN also went a bit berserk on the turrets, designing them with multiple safety features which when in service on the Nelson and Rodney proved problematic and unreliable and the kinks in the turrets were not worked out until the 1930s. The dual 6 inch pgguns of HMS Nelson, identical to the guns for the N3. The N3's were planned ot have a 15 inch belt an impressive 463 feet long whilst her armoured deck was to be 8 inches thick topped off by 14 inch thick bulkheads fore and aft to seal off the citadel, the area of the ship covered by the armoured belt. The turrets were to have armour ranging from 18 inches on their fronts to 14 inches on the sides and 8 inches on the roofs whlst the bridge was to be shileded by 15 inches of solid plate. All this on a ship that would be 815 feet long and 106 feet wide at its greatest beam.
   Cancellation
Although its doubtful that England could actually afford both the G3 AND the N3 designs at the same time as was hoped and planned, both classes fell victim to the Washington Naval Treaty which limited warships to a maximum size of 35000 tonnes, far below the N3's 59000 tonne displacement, thus a ship that could be comparable to the Yamato, just built 20 years earlier was never even laid down or ordered and the strength of the Royal Navy was for ever diminished by the Washington Treaty.