In his sketchbook, from which he was never separated from childhood, he captured views of Orléans, Tigy, Saint-Hilaire-Saint-Mesmin, before returning to Paris where he was a student of Fernand Cormon at the École nationale supérieure des Beaux-Arts (National School of Fine Arts).

[2] Asselin returned to Italy in 1910 where from Genoa he went to Naples, spent time in Rome, and finally rented a small studio in Anticoli Corrado throughout the summer, where his first works were completed on the theme of the nude.

[5] Mac Orlan wrote in his memoirs of the summer activities of Maurice Asselin and his painter friends Ricardo Florès,[Note 2] Émile Jourdan and Jacques Vaillant in Brigneau-en-Moëlan at La mère Bacon,[6] "a small fishing inn perched on a rock, located at the entrance to the jetty, which it overlooked".

Asselin, Mac Orlan, Roland Dorgelès and many other residents of Montmartre including Francis Carco and Maurice Sauvayre[Note 3] enjoyed colourful Sunday outings to the Auberge de l'Œuf dur et du Commerce in Saint-Cyr-sur-Morin.

At the instigation of General Niox, director of the Musée de l’Armée in Paris, a decree of 8 November 1916 declared that "the Under-Secretary of State for Fine Arts, with the authorisation of the Minister of War, may entrust to artists assignments with the armies".

The "modern" painters thus selected, exhibitors at the Salon d'automne and the Salon des indépendants, ranged from the former nabis (Pierre Bonnard, Édouard Vuillard, Félix Vallotton, Maurice Denis) to the "new post-Cézanne landscape painters" who at the time included Maurice Asselin, Louis Charlot,[Note 6] Henri Lebasque, Henri Ottmann, Gaston Prunier,[Note 7] and Jules-Émile Zingg, and were commissioned in this way to document history which was not yet written.

[18][19] In 1925, in the company of the painter André Fraye,[Note 10] he travelled along the Mediterranean coast (Marseille, Sainte-Maxime, Saint-Tropez), in the Var (Le Luc) and in the Vaucluse (Avignon, Orange).

Both psychological suffering (Asselin resented defeat and the Occupation) and physical pain (osteoarthritis in his hip made walking difficult) are felt in his painting, a period of "red nudes" and small bunches of flowers.

Dorival supported his argument by quoting Asselin: "if you really love painting, you will not only ask it to be a decoration for the walls of your home, but first of all to be food for your interior life.” Asselin continued: “no cerebral combination, no theory can give birth to a work of art… Art springs from the amazed love of life.”[21] “A beautiful work must, by its arrangement, its rhythm, the choice of the elements which compose it, satisfy the refined man, and, by the impression of life which it releases, move the simplest man."