Of these three powers those of Ravenna and Rome were, of course, by far the more important; for indeed the conversion of the Lombards was, rightly understood, but a part of the work of Gregory. Yet though both were working for the same end they did not always propose to march by the same road. In 592, for instance, the pope, seeing Naples the capital of the little isolated duchy upon his southern flank very hard pressed, proposed at all costs to relieve it; but the exarch Romanus, perhaps seeing further, was not to be moved to the assistance of the peasants of Campania from the all-important business of the defence of central Italy and the Flaminian Way, the line of communication between Ravenna and Rome. He proposed to let Naples look after itself and at all costs to hold Perugia. Gregory, however, who claimed in an indignant letter of this date (592) to be "far superior in place and dignity" to the exarch, proceeded to save Naples by making a sort of peace with the Lombard duchy of Spoleto. It is possible that this peace saw the Lombard established in Perugia, which was the Roman key, till now always in Roman hands, of the great line of communication between Rome and Ravenna. However that may be, Gregory's peace not only aroused great anger in Constantinople, but brought Romanus quickly south with an army to re-occupy Perugia, Orte, Todi, Ameria, and various other cities of Umbria. But Romanus had been right. His movement southward alarmed Agilulf, who immediately left Pavia, and crossing the Apennines, we may suppose,[1] as Totila had done, threatened Rome itself. Then, however, he had to face something more formidable than an imperial army. Upon the steps of S. Peter's church stood the Vicegerent of God, great S. Gregory, who alone turned him back and saved the city. [Footnote 1: All that Paulus Diaconus, _Hist. Lang_. lib. iv. cap. 8, says is: "Hac etiam tempestate Romanus Patricius et Exarchus Ravennae Romam properavit. Qui dum Ravennam revertitur retenuit civitates, quae a Langobardis tenebantur, quarum ista sunt nomma: Sutrium, Polimartium Hortas, Tuder, Ameria, Perusia, Luceolis et alias quasdam civitates. Quod factum cum regi Agilulfo nunciatum esset statim Ticino egressus cum valido exercitu civitatem Perusium petiit ..."]