Complex sentence: In June 1941 the division was moved to the Eastern Front to take part in Operation Barbarossa the invasion of the Soviet Union, they were part of the Army Group North which advanced througth the Baltic States towards Leningrad.
Split into simpler sentences: In June 1941 the division was moved to the Eastern Front to take part in Operation Barbarossa, the invasion of the Soviet Union. They were part of the Army Group North which advanced througth the Baltic States towards Leningrad.