OSSAT, ARNAUD d'. - French cardinal and diplomat, b. at Larrogue-en-Magnoac on 20 Aug. 1537, d. at Rome on 13 March 1604. In 1574 he accompanied Cardinal Paolo de Foix to Rome as secretary, and after the latter’s death (1584) he was secretary to the cardinal protectors of France, Ippolito d'Este and Francesco Joyeuse, as well as chargé d’affaires for France; he dealt with Clemente VIII in the matter of the absolution and recognition, as king, of Enrico IV di Borbone.
Acting with extreme prudence, he was able to thwart the schemes of the Spanish court, overcome the reluctance of many cardinals attached to it, and convince the Pontiff of the sincerity of the Bourbon’s conversion. Officially accredited, together with J. Daty Du Perron, for the final negotiations (July 1595), and having agreed upon the clauses and formula of absolution, he obtained recognition of Enrico IV’s legitimacy to the throne (30 Aug.); in the King’s name he made a public abjuration, receiving absolution from the Pontiff (17 Sept.). In reward for his services, he was appointed bishop of Rennes (1596), then transferred to the see of Bayeux (1600), and created cardinal (3 March 1599), while always remaining in Rome as representative of his sovereign. His abundant correspondence reveals him as a great diplomat, through his acuteness and psychological insight, combined with great disinterestedness and zeal for the Church and his country.