Le portrait équestre se définit comme le portrait d’une personne figurée à cheval hors narration.La thèse propose d’identifier et de commenter les raisons, les moyens et les finalités des cent vingt-huit portraits équestres du corpus, réalisés par des artistes italiens entre 1229 et 1511. L’analyse de l’histoire et du concept du portrait équestre italien de la fin du Moyen Age au début de la Renaissance s’articule en deux grandes parties. La première partie présente et décrit les portraits du corpus, en fonction des objets qu’ils constituent et de leurs spécificités matérielles.La seconde partie traite de leur analyse iconographique. Ces effigies qui représentent des détenteurs du commandement militaire constituent un type spécifique de portrait officiel, qui se distingue par la présence fondatrice du cheval. Caractérisé par une forte empreinte martiale, entre le début du XIIIe et le début du XVIe siècle, le portrait équestre se trouve au coeur du choc des imaginaires politiques qui anime la Péninsule. Outil d’affirmation et d’authentification du pouvoir, ce type de portrait officiel est utilisé comme instrument de légitimation, voire de propagande. / Equestrian portraits are defined as the portrait of an individual shown on horseback without any context. The dissertation proposes to identify and comment on the reasons for methods of creation and uses of the 128 equestrian portraits in the corpus of such depictions created by Italian artists between 1229 and 1511. The history and concept of Italian equestrian portraits from the end of the Medieval period to the beginning of the Renaissance are analyzed in two major sections. The first presents and describes the portraits in the corpus on the basis of object type and their specific material characteristics. The second is an iconographic analysis. These effigies which represent military commanders constitute a specific type of official portrait, which is differentiated by the fundamental presence of the horse. Typified by a strong martial imprint,between the beginning of the 13th and the beginning of the 16th century, equestrian portraits are at the heart of the conflict among political imaginations that enlivened the Peninsula at that time. A tool for the affirmation and validation of power, equestrian portraits are used as an instrument of legitimation, even of propaganda.

The content of this dissertation is the life and œuvre of Johann Georg de Hamilton, a relatively obscure painter of hunts, portraits of horses, hunting still-lifes and hunting scenes. Johann Georg de Hamilton (1672-1737), a painter belonging to a famous Scottish family, was influenced in his creative work considerably by the 17th -century Flemish painters of still-lifes and hunting scenes. He was active predominantly in Vienna and in South Bohemia, in service of Adam František, Prince of Schwarzenberg, as well as Karl VI of House Habsburg. He created hunting-themed paintings and portraits of horses to members of both the secular and the ecclesiastic aristocracy of the lands of the Austrian Empire, such as the Houses of Liechtenstein, Serényi, Althan and others. This dissertation is the very first attempt at a monographic analysis of the life and œuvre of this painter. In addition to new bibliographic data, it offers an in-depth insight into the relationship between the person who commissioned his work, Adam František, Prince of Schwarzenberg, and the painter Johann Georg de Hamilton on the basis of extant correspondence, and also attempts to present the painter's œuvre in a cultural-historical and artistic context. The dissertation mentions the first exhibition of a collection of Hamilton's work,...