ARNO, ARN or AQUILA (750?-82I), archbishop of Salzburg and scholar, entered the church at an early age, became abbot of Elnon, or St. Amand, where he made the acquaintance of Alcuin. In 785 he was made bishop of Salzburg, and in 787 was employed by Tassilo III., duke of the Bavarians, as an envoy to Charlemagne at Rome. Through Charlemagne's influence Salz burg, was made in 798 the seat of an archbishopric ; and Arno became metropolitan of Bavaria and received the pallium from Pope Leo III.
The area of his authority was extended to the east by the con quests of Charlemagne over the Avars. He acted as one of the missi dorninici, and spent some time at the court of Charlemagne, where he was known as Aquila, and his name appears as one of the signatories to the emperor's will. Soon after the death of Charlemagne in 814, Arno appears to have withdrawn from active life, although he retained his archbishopric until his death Jan. 24 821.
Aided by a deacon named Benedict, Arno drew up about 788 a catalogue of lands and proprietary rights belonging to the church in Bavaria, under the title of Indiculus or Congestum Arnonis (ed. F. Keinz, Munich, 1860. Other works produced under the protection of Arno include a Salzburg consuetudinary (ed. L. Rockinger in Quellen and Erorterungen zur bayrischen and deutschen Geschichte, Band vii. (Munich, i856). W. von Giesebrecht suggests that Arno was the author of an early section of Annales Laurissenses ma.iores, a history of the Frankish kings from 741 to 829 (Monumenta Germanzae historica Scriptores, Band i., p. 128-131. G. H. Pertz, Hanover, 1826). If this supposition be correct, Arno was the first writer whose works are extant to apply the name Deutsch (theodisca) to the German language.