Complex sentence: In April 1942, the division went to the Eastern Front near Kharkov as a subdivision of the German Sixth Army within the Army Group South for the major part of the period until surrender.
Split into simpler sentences: In April 1942, the division went to the Eastern Front near Kharkov as a subdivision of the German Sixth Army. It was to remain within the Army Group South for the major part of its service until surrender.