Which French naval architects should be blamed in 1870?
Short answerNone as a first step: French architects were then producing leading ironclads, while later strategic choices and insufficient reserves were the larger danger.
NotesThe damaging Jeune École turn came after 1870 and did not describe the fleet at the war's opening. French central-battery ironclads were then comparable to or ahead of British contemporaries. France could retain a leading naval rank by maintaining construction and preparing the coal and manpower needed to blockade Prussia. Logistics and continuity matter as much here as individual ship designs.