Austorc's only piece, "Ai! Dieus! Per qu'as facha tan gran maleza", was composed after the defeat in 1250 of the Seventh Crusade under Louis IX of France. It was Hermann Schindler who first proposed that the piece referred to the Crusade of 1250 and not that of 1270, on which Louis died. Whatever the Crusade, Kurt Lewent, whose dissertation was the first major study of Occitan Crusading songs, believed that Austorc was a combatant in it. Austorc was surprised that God would allow the Crusade's defeat, but not surprised that Christians would therefore convert to Islam. An excerpt goes like this:
Five stanzas in length, the sirventes stands incomplete: the first and last stanza contain lacunae and the final words of the tornada are lost. It is a contrafactum of a canso by Peirol, "M'entencio ai tot'en un vers mesa." Only a few years earlier another sirventes and Crusade song, "Ir'e dolors s'es dins mon cor asseza", by Ricaut Bonomel had been composed as a contrafactum of Peirol's canso.
- Alfred Jeanroy, "Le troubadour Austorc d'Aurillac et son sirventés sur la septième Croisade," Romanische Forschungen, '23 (1907), p. 82. Jeanroy edited the text and provided a French translation. He notes that a reference to Alexandria makes no sense except in the case of a date c.1250. The date 1270 was preferred by F.-J.-M. Raynouard and the Abbé Millot.
- Lewent, "Das altprovenzalische Kreuzlied," Romanische Forschungen, 21.2 (1905), p. 327.
- Austorc, Pillet-Carstens 40, 1, quoted in Jaye Puckett, "Reconmenciez novele estoire: The Troubadours and the Rhetoric of the Later Crusades," Modern Language Notes, 116.4, French Issue (September 2001:844–889), p. 878, note 59. He is also quoted in Kurt Lewent, "Old Provençal Lai, Lai on, and on," Modern Language Notes, 79.3, French Issue (May 1964:296–308), p. 302.
- The translation is Puckett's and is in prose, broken into lines here corresponding roughly to the Occitan.
- Though Raynouard did not attempt to fill in any lacunae, C. A. F. Mahn did in the first stanza, but not the fifth (Jeanroy, p. 81).
- While T.-B. Émeric-David declared Austorc "completely unknown", Camille Chabaneau identified this Austorc with the troubadour. Jeanroy, p. 86, rejects this identification, though d'Orlhac was an acceptable spelling of d'Aorlhac.