How the battlecruiser became the fast battleship

Was the battlecruiser concept an evolutionary dead end?

No. More efficient high-pressure machinery eventually made it possible to combine battlecruiser speed with battleship protection in the fast battleship.

Early battlecruisers sacrificed armour because contemporary boilers and machinery could not deliver battleship protection at the required speed within a practical displacement. By the late 1930s and 1940s, greater power per ton allowed designers to carry substantial armour without surrendering fast operational speeds. The mission did not disappear; the engineering compromise changed. The answer therefore places the fast battleship as the technological successor to the battlecruiser concept.