In the late spring of 536 Belisarius crossed into Italy, where he captured Rhegium and made his way north. Neapolis () was besieged for three weeks before the Imperial troops forced their way in during November. The largely barbarian Roman army sacked the city. Belisarius moved north to Rome, which in view of the fate of Neapolis, put up no resistance; Belisarius entered unopposed in December. The rapidity of the Byzantine advance took the Goths by surprise and the inactivity of Theodahad enraged them. After the fall of Neapolis he was deposed and replaced by Vitiges. He left Rome for Ravenna, where he married Amalasuntha's daughter Matasuntha and began rallying his forces against the invasion. Vitiges led a large force against Rome, where Belisarius, who did not have enough troops to face the Goths in the open field, had remained. The subsequent siege of Rome, the first of three in the Gothic War, lasted from March 537 to March 538. There were sallies, minor engagements and several large actions but after 1,600 Huns and Slavs arrived from Constantinople in April 537 and 5,000 men in November, the Byzantines took the offensive and their cavalry captured several towns in the Goths' rear. The imperial navy cut off the Goths from seaborne supplies, worsening their supply difficulties, and threatened Gothic civilians. The fall of Ariminum, modern Rimini, close to Ravenna, forced Vitiges to abandon the siege and withdraw.