The closely united summits of the lofty mountain ranges Haemus and Rhodope, of which the one rises immediately from the banks of the Danube and the other, from those of the Axius,In Macedonia. on our side, end with swelling hills in a narrow pass, and separate Illyricum and Thrace. On the one side they are near to the midlands of Dacia and to Serdica,See xvi. 8, 1, note. on the other they look down upon Thrace and Philippop- olis,Named from its founder, Philip I. of Macedon; modern Philibe. great and famous cities; and as if nature had fore-knowledge that the surrounding nations must come under the sway of Rome, the pass was purposely so fashioned that in former times it opened obscurely between hills lying close together, but afterwards, when our power rose to greatness and splendour, it was opened even for the passage of carts; and yet it could sometimes be so closed as to check the attempts of great leaders and mighty peoples.

The part of this pass, which faces Illy- ricum, since it rises more gently, is sometimes easily surmounted, as though it kept no guard. But the opposite side, over against Thrace, precipitous and falling sheer downward, is made difficult on both sides by rough paths, and is hard to get over even when there is no opposition. At the foot of these heights on both sides lie spacious plains, the upper one extending as far as the Julian Alps,Formerly called Venetic, xxi. 16, 7. the other so flat and open that there is no hindrance to its habitation as far as the straitThe Hellespont. and the Propontis.

After these arrangements had been made in a matter so momentous and so urgent, the emperor, leaving the commander of the cavalry there, returned to NaessusNish in Servia (Serbia). (a well-supplied town), from which he might without hindrance attend to everything that would contribute to his advantage.