After the death of his father in 1915 during World War I, Pia's mother had to work by herself.
Pia decided to move away at the age of 14 and begin a new life in Paris.
His La Muse en rut, a collection of erotic poems, appeared in 1928.
In 1938 he founded the leftist journal Alger républicain in Algiers (which was part of the French colony of Algeria at the time).
During World War II Pia participated in the French Resistance (in the group "Combat") and in 1944 he became chief editor of the clandestine resistance journal Combat, using the pseudonym Pontault.