In a land so situated and so far fallen from its earlier estate, the rapid conquests of the Osmanlis appear as due not so much to the valor and intelligence of the adherents of Islam as to the inability of the Christians to act or work together. The one security of the Empire was the comparative weakness of the Turkish sea power. The Ottoman ships were good enough for piratical expeditions, but there was no Turkish fleet at all able to cope with the navies of Genoa or Venice. At the very beginning of Murad’s accession, a consistent plan of attack was inaugurated, designed to cut off Constantinople from its “hinterland”; the objective being the trade road between the capital and Adrianople. Several of the important points on this line were taken, Murad making his residence temporarily near Demotika. According to Turkish custom, each spring brought a new expedition and a further enlargement of the existing boundaries. The siege of Adrianople itself soon began. (1360.) The Greek chronicles speak of its fall being due to a betrayal of a secret path used by peasants inside the walls to get to their fields. But the Turkish annals tell of an engagement between the garrison and the Osmanli soldiers. In the city Murad took up his residence, being attracted to it by its importance as a trading place frequented by Venetians, Genoese, Florentines, and Catalans, as well as by Turks and Greeks. Following soon the course of the river Maritza, on which Adrianople stands, the Turkish invaders moved farther into the land until they came to Philippopolis, which had been taken by the Bulgars not long before. But the Slavs showed no greater capacity than the Greeks for united action, and the town was taken from them without difficulty. Other places were added, including Berrhœa on the Hæmus, and this whole section of country for some time made up the northermost borders of Ottoman dominion in Europe. In the south the same kind of successes took place; again a trade route was selected, this time the road to Thessalonika, and a considerable stretch of the territory through which it passed was annexed. In one place the sea coast was reached at a point opposite the Island of Samothrace. Murad returned now to Broussa, interrupting a farther advance towards Trnova and Sofia, places in the hands of the Servians, whose power in war he respected and feared more than that of their allied race, the Bulgars.