The Trencavels were an important noble family in Languedoc from the 10th to the 13th centuries. At various times they ruled Agde, Albi, Béziers, Carcassonne, Nîmes, and the Razčs. The family name may derive from the words for "nut cracker" (trenca avelana).
The first well-known member of the family was Ato I, who was viscount of Albi in the early 10th century. He is followed by five generations of viscounts of Albi in direct father-to-son descent: Bernard Ato I (d. 937), Ato II (d. 942), Bernard Ato II (d. 990), Aton III (d. 1030), and Bernard Ato III (d. 1060). Each of these from Ato II on had a younger brother named Frotarius who was a bishop of Albi, Cahors, or Nîmes.
Bernard Ato III's son Raymond Bernard (d. 1074) married Ermengard of Carcassonne, sister of Roger, last Count of Carcassonne. Bernart Ato III was Viscount of Albi and Nîmes, and acquired Carcassonne and Béziers in 1068-1070 after the death of his brother-in-law. His son Bernard Ato IV (d. 1129) was Viscount of Albi, Béziers, Carcassonne, Nîmes, and Razčs. (Click on the following link for the text of a Charter by which Bernard Ato IV pays homage for some possessions to the Abbot of Lagrasse)
The sons of Bernard Ato IV divided their inheritance. The eldest, Roger I (d. 1150) took Albi, Carcassonne, and Razčs but had no children. The next, Raymond I (d. 1167) took Béziers, and inherited Albi, Carcassonne, and Razčs from his brother. The youngest, Bernard Ato V (d. 1159) inherited Nîmes and added Agde.
During this period there was considerable urban unrest as the growing cities tried to assert their independence. Raymond I was killed during one such revolt in Béziers. There was also revolts in Carcassonne in 1107 and 1120-1124. During the latter four years the Trencavels were expelled from the city.
Their complex of lands in the centre of the Languedoc gave the Trencavels considerable power in the 11th and 12th centuries. The Counts of Barcelona and Toulouse both had large territories to the east and west, and valued a potential alliance with a family that stood in the middle. For the most part the Trencavels allied with the counts of Barcelona, who became the Kings of Aragon.
The following generations were to lose it all as a result of the Crusade against the people of the Languedoc - the so-called Albigensian Crusade against the Cathars. Roger II (d. 1194), son of Raimond I, inherited his father's 4 viscounties. His son, Raymond-Roger Trencavel (1185-1209) also held them, and was captured after the fall of Carcassonne to the crusaders, having declined the offer of Raymond VI Count of Toulouse to create an alliance. He died in prison at the end of 1209. In 1247 his dispossessed son Raymond Trencavel II (1204-1263) formally ceded his rights to Louis IX of France, after several failed attempts to recover his patrimony, culminating in his siege of Carcassonne in 1240. Meanwhile, Bernard Ato V's son, Bernard Ato VI was viscount of Nîmes and Agde, had already ceded his rights to Simon de Montfort in 1214. By the time of the Cathar Crusade the Trencalels were vassals of the Kings of Aragon - a relationship which was to have many consequences, including the death in battle of the Trencavels' suzerain Peter II of Aragon, at Muret in 1213.
Click on the following link for more about Raymond-Roger
Click on the following link for more about Raymond Trencavel II
Click on the following link for more about the arms of fighters in the Cathar Wars
Click on the following link for more on Peter II of Aragon