Middle Italy was now lost to the Goths, and the scene of operations shifted into Picenum, north Etruria, and the valley of the Po, where the war was to endure for two years more (538-40). It resolved itself into a struggle for the coast towns between Ravenna and Ancona, and for the command of the passes of the Apennines. One half of the Roman army was concentrated at Rimini and Ancona, while Belisarius himself with the other was occupied in clearing the Gothic garrisons out of northern Etruria. Two Gothic armies at Ravenna and Auximum penned the northern Roman force into the narrow sea-coast plain, and at last laid siege to both Rimini and Ancona. Here Witiges seemed for once likely to succeed, but, when the garrisons had been brought to the last extremity, they were relieved by new forces from Constantinople commanded by the eunuch Narses the _praepositus sacri cubiculi_. Thrown on the defensive Witiges drew back to Ravenna, and allowed the Romans to overrun the province of Æmilia, and even to cross the Po, and raise an insurrection in the great city of Milan. There now followed a long pause: Belisarius found that Narses was set on asserting an independent authority over the newly-arrived army, and had to send to the emperor to beg him to recall the eunuch. Meanwhile he laid siege to the last two Gothic fortresses south of Ravenna, the towns of Fiesole in Etruria and Auximum (Osimo) in Picenum. Both cities made a gallant resistance, and while Belisarius was at a standstill Uraias, the warlike nephew of Witiges, stormed and sacked Milan, and restored the Gothic dominion north of the Po (539). Meanwhile the king took the only wise step which occurred to him during the whole war: he sent ambassadors to the East to inform Chosroes, king of Persia, that well-nigh the whole Roman army was occupied in Italy, and that he might overrun Syria and Mesopotamia with ease. Taken two years earlier, this step might have saved the Goths, but now it was too late: Chosroes moved, but moved only in time to hear that Witiges was dethroned and a captive. After holding out seven months, Auximum surrendered to Belisarius at mid-winter, 539-40. Witiges had done nothing to save the gallant garrison, alleging that a Frankish raid into the valley of the Po prevented him from moving. The excuse was true but insufficient, for when the Franks of Theudebert, thinned by disease, turned home again, the Gothic king did not stir any the more.