Complex sentence: The 4th Infantry Brigade was re-formed during the pre-mobilization before the outbreak of the Greco-Italian War in 1940, under the III Army Corps, which along with the II Army Corps comprised the Western Macedonia Army Section.
Split into simpler sentences: The 4th Infantry Brigade was re-formed during the pre-mobilization period before the outbreak of the Greco-Italian War in 1940. It was raised under the III Army Corps, which along with the II Army Corps comprised the Western Macedonia Army Section.