Leader: 1968–2012
Sidos set up L'Œuvre Française in 1968 and declared himself "presidor for life" (French: présideur, a portmanteau of président and dictateur). Closer to Francoist Spain and the Portuguese Estado Novo than fascist regimes, L'Œuvre Française was antisemitic, neo-Pétainist and nationalist. Sidos then seemed to endorse a blend of Catholicism, pan-European nationalism and anti-Semitism, with some Third Position influence, as his ideology of choice. Designed as a cult of personality, the organization was labeled a sect or "Church of Sidology" by critics even at the far right, while its adherents highlighted the discipline and determination allowed by their organizational style.
He attempted to run in the 1969 French presidential election on this platform, seeking to stand as a nationalist and anti-Zionist candidate, but his candidacy was rejected by the Constitutional Council on a technical basis. It has been argued that there was a fear any judgement in Sidos' favour would have been considered a vindication of his collaborationist background in wider society. Le Soleil, organ of L'Œuvre Française, dismissed the Jewish origin of some members in the council, namely Gaston Palewski and René Cassin, as the reason for their refusal. In 1973, Sidos was the only candidate for L'Œuvre in the legislative election. Sidos was said to have met António Salazar for a short encounter in the 1960s, king Faisal of Saudi Arabia for a one-hour meeting on 28 April 1971 in Riyadh, as well as Juan Perón on 22 October of the following year in Madrid, and former SS colonel Otto Skorzeny in the same city. According to Sidos, Perón declared to him that "Paris [had] been the world capital of subversion since 1789."
By the 1980s he had come to moderate his own position and sought to build a wider alliance with other fringe right-wing movements, including monarchists, integrists and the supporters of Marcel Lefebvre. To this end he joined François Brigneau, Pierre Pujo and Jean Madiran in a commemoration service for the tenth anniversary of the occupation of Saint-Nicolas-du-Chardonnet by the Society of St. Pius X in 1987. Sidos subsequently sought co-operation with the Front National (FN) although at other times he would dismiss the party as too moderate. In 1996, he announced the rallying of L'Œuvre to the party, despite the opposition of his right hand man Yvan Benedetti.
After negotiations with Sidos, Jean-Marie Le Pen eventually allowed some L'Œuvre militants to integrate the FN in 2007. The party however later tightened its policy regarding the association, Marine Le Pen denouncing an "operation of entryism" to facilitate the seizure of power by her rival Bruno Gollnisch in the FN. Following Jean-Marie Le Pen's departure from the leadership in 2011, replaced by his daughter Marine, Sidos severed all ties with the party, telling far-right newspaper Rivarol that he did not feel a woman should have such an important position.
In 2012, at 85, he left the presidency of L'Œuvre Française, succeeded by Yvan Benedetti.