French architect (originally named Pierre Michel), he was an early protagonist of Neo-Classicism in Germany, making a career there by passing himself off as an academically-trained architect with an aristocratically-resonant name (he was actually a joiner who had worked on various jobs, including stage scenery) and by employing competent draughtsmen to work up his designs into presentation drawings. In 1764 he was employed by Prince Joseph Wilhelm von Hohenzollern-Hechingen (1717–98) to remodel various interiors (destroyed), and he designed sundry works for the Swabian aristocracy. His big chance came when he was commissioned to rebuild the Benedictine monastery and church of St Blasius at St Blasien, Waldshut, in the Black Forest (begun 1772). With its great domed space surrounded by free-standing Corinthian columns, and choir also featuring columns, the inspiration was clearly the Chapel at Versailles and the Pantheon: St Blasius was the first significant Neo-Classical building in Southern Germany, and was completed under the direction of Pigage when d'Ixnard's contract was cancelled in 1774. D'Ixnard designed the Church of Sts Cornelius and Cyprian, Bad Buchau (1773–6), and in 1777 was commissioned by Clemens Wenzeslaus, Elector and Archbishop of Trier (1768–94) to prepare designs for a vast Residenz (Seat of the Court) at Koblenz, with a Giant Order of columns and pilasters to unify the scheme, and a dome over the corps-de-logis. Although work started in 1778, the design was adversely criticized, and a reduced version of the palace was erected to designs by A.-F. Peyre from 1779. D'Ixnard also prepared designs for a series of crescents and circuses within a grid-plan for Clemensstadt, later Neustadt, Koblenz (1777), a spacious new town, also for the Archbishop-Elector: it was partly realized. His designs for the Residenz were published in his Recueil d'Architecture (1791), which demonstrated his advanced Neo-Classical style. Other works by D'Ixnard include the hall of the Merchants' Guild, Zum Spiegel, Strasbourg (1782–5), the church at Hechingen, near Stuttgart (1780–3), the library of the Collège Royal, Colmar (1785–7), and the Church at Epfig (1790–1).
E. Franz (1985);Ixnard (1791); Jahrbuch der staatlichen Kunstsammlungen in Baden-Württemberg, vi (1969), 161–8;Jane Turner (1996);Watkin & Mellinghoff (1987);Wallraf-Richartz-Jahrbuch, liii (1992), 155–75