Dunoyer was born in Boussy-Saint-Antoine and spent his childhood there and in Paris. His parents wanted him to attend the military academy of Saint-Cyr but, recognizing his strong interest in drawing, they agreed to his enrollment at the Free Academy of Luc-Olivier Merson. Merson's academic style of instruction did not suit Segonzac, however, and, following a period of military service, he studied at the Académie de la Palette, whose staff included Jacques Émile Blanche. Soon giving this up in favor of an independent course he later cited 1906 as the starting date of his artistic career.
In 1914, the year of his first solo exhibition (at the Galerie Levesque in Paris), he was drafted for military service in
World War I. He saw combat in the region of Nancy and at
Bois-Le-Prêtre, before being transferred to the camouflage section. Between 1914–1918 he published and exhibited a number of war drawings, and by war's end he had earned the
Croix de Guerre. He drew on his military experiences—and learned
etching in 1919—in order to illustrate
The Wooden Crosses by
Roland Dorgelès (published in 1921). Segonzac found etching to be a congenial medium to his spontaneous drawing style, and by the end of his life he had produced some 1600 plates.
The gossamer quality of his etchings stood in contrast to the thickly painted surfaces and generally somber color of his
oil paintings, which reflected his admiration for
Courbet and
Cézanne. His subjects include
landscapes,
still lifes, and
nudes. Prolific until the very end of his life as a painter in oils and
watercolor, and as a printmaker, Segonzac died at age 90 in 1974.