Unlike the rest of the department the Fenouilledes was already under French rule even before the Treaty of the Pyrénées which defined the borders between France and Spain.
It was in 1258 with the Treaty de Corbeil that the Fenouillèdes became French territory where as the rest of the region was part of Spanish Catalonia. The French army having already annexed the castles where the Cathars took refuge. This time was seen as an ideal opportunity to put down the rebellion against the Church that was being established by the "Bons hommes" (good men) and "Bonnes femmes (good women), also called the "Parfait" or "faydits" … the famous Cathars.
the cathar period
The ‘Parfaits’ were opposed to the overbearing power of the Roman Catholic Church especially in regard to its excesses and corruptions and they deemed it to have strayed far from true faith and religion. They choose instead to adopt a more simple and chaste lifestyle albeit often to the extreme. The movement started among the nobles and bourgeois classes but then eventually it extended through to all the social classes.
The southern Lords took the Cathars or Albigensians under their protection welcoming them into their castles, mostly around the Toulouse area (Foix, Albi, Peyrepertuse, etc.). The southern Lords were probably more open to the anti conformist Cathar (or Albigensian) movement because they themselves were already seeking more autonomy and eventual independence from the French crown.
Although the Parfaits or Perfecti took refuge in the castles which we now call « châteaux cathares », they did not, in actual fact, build any of these Castles. Their faith was founded on simplicity and they rejected many worldly comforts and material values. They were regarded as heretics by the Roman Catholic Church. The eradication of heresy intensified during the time of Pope Innocent III during the 12th century and later in the 13th century. With the blessing of the Pope the crusade against the Albigensians began in 1208 and was the first ever crusade to be undertaken on Christian soil.
From the crusade against the Albigensians up to the Treaty des Pyrénées
This desire for the church to eradicate those who challenge its supremacy coincided with the French political and military will to bring to submission the southern Lords who sought independence from the French crown. En 1240, The château de Peyrepertuse lost it’s independence and resubmitted to French rule. Later in 1250 the château de Puilaurens followed suit.
Château de Quéribus accepted the yoke of the French army, in May 1255. In August, reconstruction began on all three Castles for accommodating the army. In 1258, the Château de St-Pierre in Fenouillet also came the possession of the French, and France signed an agreement with the crown of Aragon called the Treaty of Corbeil which in effect redefined the frontier between France and Spain. This was marked by boundary stones that are still visible around the limits of the Fenouilledes, most notably around Latour-de-France and Bélesta. The Fenouillèdes became part of France and all of Catalonia was annexed to the kingdom of Aragon. The Fenouilledes thereafter became a place of ongoing conflict between the two kingdoms which caused much poverty and misery for the inhabitants of the region. A way out was later found in the Treaty des Pyrénées, in 1659, when the border between France and Spain finally became the frontier as we now know it with Catalonia becoming split into two parts, one part in Spain and the other in France.
The creation of departments (counties or shires)
In 1790, The Assemblée Constituante voted in a decree which defined the limits and names of the departments. The Fenouilledes was split into two parts, one part in the department of Aude and the other in the department of the Pyrénées Orientales, along with French Catalonia.
This variation in historical roots explains why there are so many cultural differences on a local level.