English summary: John Pierpont Morgan (1837-1913), who enjoyed enormous prestige in financial circles, is viewed as the guardian of American capitalism. The bank which he founded - J. P. Morgan Bank - is one of the most influential in the world. In the mid-19th century, America was a nation that had yet to be developed. J. P. Morgan understood that in order to meet the country's enormous needs, strength could be found in unity. He therefore set up huge businesses - trusts - in the railroad, steel, electricity, telephone and maritime transport industries, in which the latest technological advances could be implemented. He sponsored the Titanic, the sinking of which was the sole failure of his career. At the very last possible moment, the Federal Government called upon him to prevent America from going bankrupt. As an admirer of France and a dedicated collector, J. P. Morgan spent nearly five months of every year in Europe - most of the time in Paris - where he bought thousands of works of art. An extraordinary person, he marked his century and his country, and contributed to the rise in economic and political power of a nation that would soon lead the world.Anne Kraatz who holds a doctorate from the Ecole Pratique des Hautes Etudes, has already published many books at les Belles Lettres: Mode et philosophie ou le neoplatonisme en silhouette, 1470-1500 (2005); Histoire du commerce franco-russe, concurrence et contrefacons, de Colbert a 1900 (2006) and Luxe et luxure a la cour des papes de la Renaissance (2010). She's American and she worked six months on Morgan Archives. French description: On l'a appele le Saint Patron du capitalisme, le Napoleon de Wall Street, le Vieux, etc., mais ce sont ses initiales, J. P. qui sont restees dans la memoire americaine avec le nom de la banque JPMorgan. John Pierpont Morgan est considere comme la figure tutelaire du capitalisme americain et jouit, encore aujourd'hui, d'un immense prestige dans les milieux financiers. Au milieu du XIXe siecle, l'Amerique est un pays ou tout est a prendre et tout est a construire. J. P. met donc sur pied de gigantesques entreprises, les trusts, ou sont mises en oeuvre les dernieres inventions technologiques, que ce soit dans les chemins de fer, l'acier, l'electricite, le telephone ou les transports maritimes. Il est le commanditaire du Titanic, dont le naufrage sera le seul echec de sa carriere. Le gouvernement federal fait appel a lui pour empecher in extremis l'Amerique de faire faillite. Grand ami de la France et grand collectionneur, J. P. Morgan passe quasiment cinq mois par an en Europe, surtout a Paris ou il achete des milliers d'objets d'art, ou encore a Aix-les-Bains ou il prend les eaux. Personnage hors du commun, toujours en voyage, aimant les femmes et la bonne chere, passionne d'art et d'histoire avant que de finance, il a marque son siecle en contribuant a la montee en puissance economique et politique d'une Amerique qui allait bientot dominer le monde.