Complex sentence: He was trained as a newsreel cameraman at the German susbsidiary of the French film production company Gaumont in 1912 and remained with them until the end of World War I. During the war, he chronicled battles in the Middle East and in Russia.
Split into simpler sentences: He was trained as a newsreel cameraman at the German susbsidiary of the French film production company Gaumont in 1912. During World War I he chronicled battles in the Middle East and in Russia.