Complex sentence: In January 1943, Vatutin relentlessly drove Germans from Eastern Ukraine, his offense enabled Voronezh Front of General Filipp Golikov to capture Kharkov, but he overextended his depleted troops and did not pay enough attention to changing intelligence situation.
Split into simpler sentences: In January 1943, Vatutin relentlessly drove Germans from the Eastern Ukraine. His offense enabled the Voronezh Front of General Filipp Golikov to capture Kharkov, but he overextended his depleted troops and did not pay enough attention to the changing intelligence situation.