The overall demographic decline had two important consequences: shortage of manpower became a principal factor in imperial policy, and this in turn transformed the landscape of the empire. Human spoils, the captives who followed in the train of victorious armies, were a constant feature of the wars against the Arabs, Bulgars and Slavs. Prisoner exchanges and the refusal to hand over fugitives are more often mentioned in Arabic sources than in Byzantine ones, but show that manpower had become a precious commodity; the withholding of captives led to the disastrous campaign against the Bulgars at Bersinikia in 813.38 The emperors conducted a veritable settlement policy. Constantine V and Leo IV settled prisoners taken on the Arab border – from Germanikeia, Melitene and Theodosioupolis – in newly-constructed kastra in Thrace.39 Constantine repopulated Constantinople in 756 with natives of Greece and the islands,40 and in the 760s he installed migrant Slavs on the Asiatic coast of the Black Sea near the Bosporus.41 But it was Nikephoros I who pursued a settlement policy most vigorously. According to Theophanes’ Chronicle, in 807 he began by moving to Thrace people in Asia Minor found to be without fixed homes, and in 809–10 he settled impoverished soldiers from the themes of Asia in the Sklaviniai of Greece and Macedonia. The so-called Chronicle of Monemvasia corroborates Theophanes’ information for the region of Sparta.42 Later, according to the Life of Athanasia of Aegina, manpower shortages forced Theophilos to issue an edict requiring Roman widows to marry barbarian immigrants.43 Likewise, Theophilos adopted the policy of settling defectors from the caliphate in Asia Minor: initially the Banu Habib of Nisibis were installed as freebooters on the border, and the famous Persian unit commanded by Theophobos was transferred to the regions of Sinope and Amastris, later to be dispersed throughout the themes (see below, p. 393).44 The empire required men, both to join the army and to pay the taxes which provided for its upkeep: this could explain both the forced conversion under Leo III of the Jews andMontanists,45 and also the persecution of monks by Constantine V between 767 and 770, forcing them to return to lay status and marry.46 The scarcity of men also transformed the landscape and economy of the empire between the end of the sixth century and the seventh. Certain regions, such as Mount Athos, were abandoned and would not be repopulated until the ninth century.47 The empire was no longer a network of cities, but rather a rural state supervised from Constantinople, the metropolis which survived behind its walls. The fate of the cities of antiquity has been much studied48 and there is agreement that the standard model – that of cities being abandoned for fortresses or refuges built on higher ground – needs refining. To begin with, a large number of cities were abandoned outright – including Anemurion49 and Tyana – even if some, such as Pergamon, revived in the tenth century.50 However, despite could cite the case of Locri, abandoned for Gerace (Hagia Kyriake) before 78751 and examples from Asia Minor are legion52 – the inhabitants often remained inside the ruined city, even when they had no means of rebuilding it: they withdrew to a defensive position, fortifying only a small part of the city with materials from the ruins. Such was the case at Ankyra,53 Amorion,54 Side55 and Sardis.56 Ephesos combines the two patterns: one small part of the ancient city surrounding the port was reused and fortified, and a fortress was built on higher ground nearby, around the cathedral of St John (now Selc¸uk).57 Furthermore, fortifying a reduced space was in no way incompatible with small groups living in other districts inside the perimeter of the ancient city, as at Amorion, or with the presence of a kastron on higher ground further off, as is well illustrated by the Miracles of St Theodore at Euchaita under Constantine V.58 Finally, there were the cities created on virgin sites or on the sites of ancient fortresses, strongholds on high ground which contained the newly constituted civil, ecclesiastical and military administration within their walls. Such were the Thracian kastra of Probaton and Bulgarophygon constructed under Constantine V,59 ranking high on the list of bishoprics, or Santa Severina (Nikopolis) in Calabria.60 There were many variants, but the essential pattern was that cities shrank to a quarter of their previous size; all of them – whether old or new – were now fortified and their main function had changed. The city had become above all a local branch of the state; both from a military point of view – as garrisons or refuges for the surrounding rural population – and from an ecclestiastical perspective – as the residence of the bishop. However, it should be noted that the economic function of the city as a place for markets and fairs did not disappear. In the context of the demographic and economic depression shown by numismatic records, the written sources sometimes give paradoxical information; one example is the remission by Constantine VI of fees amounting to 100 pounds of gold (7,200 nomismata) for the fair of St John at Ephesos in 795 – an enormous sum which continues to puzzle historians.61 One explanation might be the industry of local peasants, whose villages (ch¯oria) had become the basic unit of the fiscal system, so vividly pictured in the Farmer’s law.62 Indeed, the Arabic geographers describe the empire as having no cities and being made up of prosperous districts with fortresses and villages, often in caves or underground.