Having reached the rank of Lieutenant, Demetrescu-Buzău was again called under arms when Romania joined the Entente Powers. In one account, he saw action against the Central Powers in Moldavia, following the Army's northward retreat. However, this is partly contradicted by his correspondence from Moldavia, which shows that his new office was as a quartermaster, and which records his frustration at not having been allowed to fight in the trenches. According to another account, he was mostly bedridden with malaria, and therefore unable to perform any military duty.