When war was declared in 1914, he took the bold step of volunteering as an auxiliary doctor. During his leave, he focused intently on his research for « Le Cheval », a work that would become the cornerstone of his career.

In late November 1916, he was hospitalized with typhoid fever, contracted from caring for the sick. While there, he was treated by Professor Gosset, with whom he forged a lasting friendship and painted a notable portrait.

Unfortunately, Duchamp-Villon’s life was cut short when he passed away on October 7, 1918. His brothers, Jacques Villon and Marcel Duchamp, took charge of overseeing the casting of his bronze sculptures and the enlargement of his works, ensuring they were realized in strict accordance with the artist’s intentions.