Siege of Bari The siege of Bari took place 1068 – 71 , during the Middle Ages , when Norman forces , under the command of Robert Guiscard , laid siege to the city of Bari , a major stronghold of the Byzantines in Italy and the capital of the Catepanate of Italy , starting from August 5 , 1068 . Bari was captured on April 16 , 1071 when Robert Guiscard entered the city , ending the Byzantine presence in southern Italy . History . Background . By 1060 , only a few coastal cities in Apulia were still in Byzantine hands : during the previous few decades , the Normans had increased their possessions in southern Italy and now aimed to the complete expulsion of the Byzantines from the peninsula before concentrating on the conquest of Sicily , then mostly under Islamic domination . Large military units were thus called from Sicily and , under Count Geoffrey of Conversano , laid siege to Otranto . The siege . The next move was the arrival of Robert Guiscard , with a large corps , who laid siege to the Byzantine of Bari on 5 August 1068 . Within the city there were two parties : one wanting to preserve allegiance to the Byzantine empire , and another that was pro - Norman . When the Norman troops neared , the former had prevailed and the local barons shut the city ' s gates and sent an embassy to emperor Romanos IV Diogenes in order to seek military help . The negotiations offered by Robert were refused . Otranto fell in October , but at Bari the Norman attacks against the walls were repeatedly pushed back by the Byzantines . Robert decided to blockade the city ' s port with a fortified bridge in order to thwart any relief effort . The Byzantines , however , destroyed the bridge , and managed to maintain a link with their homeland . Romanos IV named a new catepan , Avartuteles , and provided him with a fleet with men and supplies for Bari . The Byzantine fleet arrived at the city in early 1069 , but in the meantime a Byzantine field army was defeated by the Normans , who occupied Gravina and Obbiano . Robert did not return immediately to Bari , and in the January 1070 he moved to Brindisi to help the Norman forces then besieging that coastal fortress . Brindisi capitulated in the autumn of 1070 . The situation in Bari was then critical , and the population suffered from famine . Avartuteles plotted to have Robert assassinated , but the Byzantine " patricius " Byzantios Guideliku failed . A delegation of citizens asked the catepan to improve the city ' s defence , or otherwise surrender it to the Normans . Avartuteles played for time , sending another embassy to Constantinople . He obtained the arrival of a fleet with grain in Bari . When the grain ran out , a group of citizens again asked the catepan to beg the emperor to send an army as soon as possible . Romanos IV , whose generals had been repeatedly defeated by the Normans , and with few free troops to dispatch , sent twenty ships under the command of a Gocelin , a Norman rebel who had taken shelter in Constantinople . Stephen Pateran , appointed as new catepan of Italy , came with him . However , the Normans intercepted the Byzantine ships off Bari and scattered them . The Norman sailors identified Gocelin ' s ship and , despite the loss of 150 men , finally captured it ; Stephen was instead able to reach Bari . He soon recognized that the defence had become impossible ; a local noble , Argyritsos , was sent to negotiate with the Normans . The latter offered acceptable conditions , and Bari surrendered on April 1071 . Aftermath . Stephen Pateran was initially imprisoned , but was later allowed to return to Constantinople with other Byzantine survivors . With the fall of Bari , the Byzantine presence in southern Italy ended after 536 years . Emperor Manuel I Komnenos tried to reconquer southern Italy in 1156 - 1158 , but the attempt turned into a failure .