Zervas was a Venizelist, and in 1916 was among the first to join the venizelist Movement of National Defense in Thessaloniki. He served with distinction in many battles of the Macedonian front during World War I, being eventually promoted to major.
Zervas was a member of the Venizelist Movement, which advocated for national defense. In 1916, he joined this movement's effort in Thessaloniki and served with distinction in many battles on the Macedonian front during World War I, eventually achieving the rank of major.