Complex sentence: Further Soviet offensives against Army Group Centre-the Gomel and Orsha Operations in November 1943 and the Vitebsk Operation in February 1944 were unsuccessful against the strong Ostwall defences however the Soviets did succeed in almost encircling the heavily fortified town of Vitebsk.
Split into simpler sentences: Further Soviet offensives against Army Group Centre-the Gomel and Orsha Operations in November 1943 and the Vitebsk Operation in February 1944 were unsuccessful against the strong Ostwall defences. However, the Soviets did succeed in almost encircling the heavily fortified town of Vitebsk.