Following forced nationalization Société Nationale de Constructions Aéronautiques du Sud-Est formed December 1936, taking over Levallois-Perret and Argenteuil plants of LeO (but not Rochefort), all Romano and SPCA and Sartrouville factory of Potez-CAMS. From 1 January 1941 took over SNCA du Midi, which went into liquidation. Continued production of D.520 and LeO 45. Post-1944 produced 27 prototypes, but staple products included Vampire (DH licence) and Nene-engined Mistral, Languedoc (ex-Bloch/SE 161), Caravelle (27 May 1955), S-55 and S-58 helicopters (Sikorsky licence) and Alouette helicopter (12 March 1955). Amalgamated with Ouest-Aviation 1 March 1957 to form Sud-Aviation. This amalgamated with Nord and SEREB 1 January 1970 to form Aerospatiale.