Complex sentence: The army subsequently fought in southern Poland, Silesia, and the Berlin Operation, overrunning the OKH command post at Zossen (headquarters for German Eastern Front operations) on April 21,1945.
Split into simpler sentences: The army subsequently fought in southern Poland, Silesia, and in the Battle of Berlin. It overran the OKH command post at Zossen, headquarters for German Eastern Front operations, on April 21,1945.