The Nivellement Général de la France network was re-established by the IGN starting in 1962.
Notes on verification
Confirmed by IGN's own official site, corroborated independently by French Wikipedia, a CNIG technical PDF, and the AFT topography glossary. All sources agree on 1962-1969 timeframe. [cascade flags: wikipedia_dropped_other_sources_exist | tier=silver indep_score=0.925 clusters=2 claim_tier=notable | framework convergence=partial on Historical record of IGN's re-leveling campaign (réseau IGN69), documented in IGN's institutional history and subsequently referenced by government/professional geodesy bodies (upstreams: Institut Géographique National (IGN), CNIG (Conseil National de l'Information Géographique)) — publishers independent, evidence may not be | kind=empirical eligibility=high]
Sources
- Le nivellement - Géodésie (seed:geography_and_travel)
- https://cnig.gouv.fr/IMG/documents_wordpress/2017/08/Lavoue_IGN_Evolution-Reference-Verticale-France.pdf (corroboration)
- https://www.aftopo.org/lexique/nivellement-general-la-france-reseau-du/ (corroboration)