Question: Who developed this defensive plan in the 1880s that has Fort de Cindey as one of its three principal fortified regions?
Sentence (from "Fort de Cindey"): The Fort de Cindey was built in two steps: the first, between 1941 and 1946 and the second step, between 1948 and 1954 (the hospital, the artilleries casemates with the gunnery command and the ammunition magazines) .
Relevant evidence: No