Complex sentence: Bari, the capital of the Byzantine catapanate, was besieged by the Normans beginning in August 1068; in April 1071 the city fell, and the last outpost of Byzantine government in Western Europe disappeared.
Split into simpler sentences: Bari, the capital of the Byzantine catapanate, was besieged by the Normans from August 1068. In April 1071 the city fell and the last outpost of Byzantine government in Western Europe disappeared.