Pau, Pyrénées-Atlantiques
Poeymirau was born in Pau, Pyrénées-Atlantiques on November 8, 1869 and is the son of André Adolphe Poeymirau, a business man, and his wife Delphine Rocacher. He studied at the Collège Stanislas de Paris, then the Military School of Saint-Cyr Coetquidan before being accepted to the War College.