Noël Édouard, vicomte de Curières de Castelnau was a French army general, army group commander and Chief of Staff of the Armed Forces during the First World War. Elected deputy in 1919 and president of the Army Commission in the legislature, he then took the head of a confessional political movement, the Fédération Nationale Catholique. During the Second World War, he opposed Marshal Pétain and the Vichy regime and supported the French Resistance. For a long time controversial because of a Catholicism that was considered outrageous by his opponents, historians have moderated that portrait by emphasising his great loyalty to republican institutions and disputed in particular that he could have been reactionary or anti-Semitic.

The Fédération Nationale Catholique (FNC) was a French movement that was active in the 1920s and 1930s, with the purpose of defending the Catholic Church against secular trends in the governments of the time. The Federation was founded in 1924 in response to the election of a left-wing government with a secularist policy. After rapidly gaining members and staging large demonstrations, it soon achieved its goal of maintaining the status quo separation between church and state. The movement gradually lost momentum in the years that followed, although it remained in existence during the Vichy regime.