The "fast battleship" fulfilled Admiral Fisher's requirement

Prior to the Great War, Admiral Fisher had advocated that the only capital ship be a fast, well-armed battlecruiser that could make at least 30 knots. The universal adoption of the fast battleship by all the major powers was a recognition of his vision. Of the fast battleships, the North Carolina and Washington were perhaps the most poorly protected. They were inferior to the Scharnhorst and Gneisenau, in may ways. Those last two were very nearly a continuation of the earlier German vision of the battlecruiser, with better protection and lighter guns than the British ship. Most of the "fast battleships" were not fast enough. The Iowa class were the best of the Allied ships, although the Vanguard was almost a modern analog to the Hood, with protection issues fixed. Admiral Fisher's "Super Lion" proposal from 1912 (10-15in guns and 30 knots) were fast battleships without the heavier armor. I still estimate that they could have had 9in side armor, which was sufficient, as the Lion, Princess Royal, Queen Mary, and Tiger proved. They had 9in over the machinery, but I believe that they had only 5in over the magazines, which is pretty amazing.