Pierre Dumont came from a bourgeois family in Rouen who did not take kindly to his decision to become a painter. He founded the XXX Group in Rouen, and then the Société Normande de Peinture (Normandy Painting Society), whose members included Joseph Delattre, Jacques Villon and Marcel Duchamp. Utrillo, Vlaminck, Guillaumin and Luce also sent paintings to the Society's exhibitions from Paris. The local art critic from the Rouen Daily ( Journal de Rouen) published an article on Dumont and bought one of his paintings. Dumont also contributed to the Rouen-Gazette with an enthusiastic article on Jacques Villon which he dictated to his friend Varenne. In 1912 he founded a short-lived publication, The Golden Section ( La Section d'Or). This preceded the exhibition of the same name organised by Villon in Paris, which featured three paintings by Dumont. Apollinaire and Reverdy submitted articles for his review, and Dumont invited Apollinaire to Rouen to give a talk on Cubism. Dumont was also an acquaintance of Picabia. He settled in Paris, in one of the Bateau-Lavoir studios, where he met Juan Gris, Max Jacob and others. After distancing himself from the Cubists and resuming his personal style, Dumont went through a period of signing his paintings Jallot. He visited the Jura region in around 1916, as well as Provence and Marseilles. He was well-known and highly regarded by 1927 when, during a visit to Rouen, he suffered the first of many bouts of mental illness.Dumont's earliest paintings were influenced by Van Gogh and Cézanne, and had a liveliness that recalled Fauvism. Subjects from this period included landscapes of Varengeville, Eauplet and the Île Brouilly. During bad weather, he took refuge in his studio and painted colourful still-lifes. From about 1910, he began producing paintings of Rouen Cathedral, which became one of the major themes in his work. From 1914 to 1919, most of his work depicted the streets of Montmartre, Notre-Dame Cathedral, Parisian bridges and the quays along the Seine. His adherence to Cubism did not last long, as his taste for vibrant colour distanced him from Cubist orthodoxy. He returned to his flamboyant palette and to the broad, energetic brushstrokes and thick impasto that remained the hallmark of his style.
Until 1918, Dumont took part in the Salon des Artistes Indépendants and the Salon d'Automne as an Orphic Cubist; one of the categories of Cubism defined by Apollinaire. His solo exhibitions included a collection shown in 1909 hosted by Legrip, the art dealer and champion of the progressive artists of Rouen. Posthumously, his work featured in the 2003 group exhibition Around Impressionism: Nineteen Painters from the School of Normandy ( Autour de l'Impressionnisme: dix-neuf peintres de l'école normande) in the Maison des Arts in Antony (Hauts-de-Seine). There have been regular retrospective exhibitions of his work, including at the Galerie M. Denis in Paris in 1944. A major collection of his paintings - both from Paris and from Normandy - was shown at the Galerie Katia Granoff in Paris in 1988.