Dominicans William Arnaud, Bernard of Rochefort and Gracia of Aure were the first inquisitors in Languedoc. They lived in the monastery of St. James in Toulouse. Along with several companions from the Order of St. St. Francis (Stephen of Narbonne and Raymond of Carbonne) and the diocesan clergy went to Avignonet in the Diocese of Toulouse for a disputation with the Albigenses. Although the faithful warned them of the danger, they went to the meeting. They accepted hospitality at Raymond VII's castle, thus falling into an ambush prepared by the city's governor. Wilhelm, seeing the ambush, intoned the Te Deum hymn, which his comrades took up. And they died while he was singing. This took place at night of May 28-29, 1242, during the Ascension of the Lord.
A description of their martyrdom was given by one of the first Dominican chroniclers, Gérard de Frachet (1205-1271). He reports that at the time of their deaths, people had a vision of them ascending to heaven in several places. "On the night it happened to them," he wrote in his Vitae Fratrum, "a woman from the same diocese, but in a different city, exclaimed while giving a birth: ‘I see the sky open up and the ladder come down to the ground, and a lot of blood is spilled on the ground.’ As she looked at the brightness of the ladder and admired the redness of those who climbed it, she gave birth without noticing the pain. Some shepherds keeping guard in the same area saw the same. Also, the illustrious King James of Arragon, who was keeping vigil on the border with the Muslims that same night, saw a great light from heaven and said to his soldiers: ‘Be assured that God did something wonderful that night.’ Similarly, in our monastery in Barcelona, that night many of the brothers saw the heavens open and light descending, illuminating the entire sky."
In some accounts, slightly different information can be found, but only on the level of detail. For example, they mention that during the massacre the martyrs sang the Salve Regina. We learn that the attackers came out at them with axes and swords. Hence, iconography depicts them with severed heads, which they hold in their hands. This is also how they are presented in the cloisters of the Santo Domingo Monastery, however, not together, but each separately. But there are also images that clearly show them as they are being martyred and/or as they enter heaven with the palms of martyrdom, and are greeted by the Blessed Virgin Mary, protector and patroness of the Order of Preachers.
The assassins took mementos from the murdered and kept them with great joy, thinking that with their deaths came an end to the Inquisition in their area. In addition, some of them dressed up in Dominican habits and jokingly encouraged associates to come and listen to Guillaume Arnaud's sermon.
The three murdered Dominicans were buried in the church of St. James in Toulouse, while the Franciscans have their church in the same city.
Since there was a vacancy on the papal throne at the time, however, the cardinals wrote to the Dominican community in Toulouse, reminding them that St. Dominic founded the Order of Preachers to stamp out heresy, but also offering condolences for the death of these "spiritual doctors" and "servants of God" who "became holy martyrs of Jesus Christ." As early as 1243, the new Pope Innocent IV issued the bull Inter alia desiderabilia, in which he expressed his belief that these murdered Dominican inquisitors "are included in the community of martyrs." Nonetheless, the pope was not interested in their canonization, probably for political reasons, in which he wanted to involve Raymond VII.Although the records of the general chapters of the Order of Preachers at the time do not explicitly mention undertaking the canonization of these martyrs (the case of Peter of Verona was different), the order still demanded that the Pope elevate them to the altars. However, Innocent IV kept refusing. This did not prevent the monks from preaching about their holiness. As it turned out, this papal statement that they were among the martyrs was enough. From then on, their relics were kept and venerated by the entire order, and the brothers were considered saints. However, their cult was not officially approved until September 6, 1866, by Pope Pius IX. Their memorial falls on May 29, the anniversary of their martyrdom.
As an aside, it is worth mentioning that in the calendar of saints, blessed and famous Dominicans published in the 18th century by Polish Dominican Michał Siejkowski, included in Dni roczne , there is no mention of these martyrs, at least under the date of May 28 or 29. The Toulouse martyrs are remembered on January 30. However, the reference here is to the six Servants of God murdered by the Albigensians: Nicholas, Peter, two Johns, Edmund and Robert. He writes of them that "being cut down, they arose, and each of them bore his head to the altar to his church."