The conquest of the Straits by the Ottoman Turks

The conquest of the Straits by the Ottoman Turks was a gradual one, extending over a century. Their predecessors in Asia Minor, the Seljuk Turks, whose rise in the eleventh century was one of the chief causes of the Crusades, had suffered both from civil war and from the Mongol invasion so that the Greeks in Byzantium were able to maintain even their feeble hold on the Asiatic shore. But in the closing years of the thirteenth century the chieftain of a new band of war refugees from central Asia, Osman I --whence the name Osmanli or Ottoman--carved out for himself a new sultanate, the foundations of which were laid by defeating the Greeks of Byzantium, so that he could reach to the Sea of Marmara. His son Orkhan, after the conquest of practically the entire southern coast of the sea and straits, profiting from Greek dissension and treachery, sent an expedition across into Europe about 1350, under his son, Suleiman. Finding the country open to him, Suleiman finally crossed the Dardanelles and seized and fortified Gallipoli in 1356. From that time, with but slight intervals, the Ottoman Turks have held the fortifications on both sides of the Dardanelles, which at this point are only about a mile in width. Meanwhile they proceeded with the conquest of the hinterland, overrunning Thrace and establishing their capital in Adrianople in 1367.

For almost a century after the Turks had taken the ports on the Dardanelles, Constantinople still held its own against the apparently inevitable fate. The explanation of this anomaly is not to be found in any heroic mood or religious fervor of crusade upon the part of the Greeks, but rather in the general international situation which the passage of the Dardanelles by the Turks had brought about. For the Italian traders were now genuinely concerned with Turkish policy, as they had formerly been--and still continued to be--with Byzantine. So Genoa by diplomacy ( 1387), and Venice by war ( 1416), won from the Turks the concession of a free Dardanelles. It was a precarious freedom, but so long as sea-power remained to the Genoese and Venetian fleets, the possession of the land fortifications was not enough to secure the control of the passage. That had to await the invention of heavy artillery.

It was not at the Dardanelles but at the Bosphorus that the Turks finally established their control of the Straits. It should be recalled that the closure of the former presents an entirely different problem from the closure of the latter. The Dardanelles could be opened to Christian shipping, by special grants to European states, in order to reach Constantinople. But the Bosphorus holds the key to the Black Sea. Turkish control of it was a first step in the taking of Constantinople. The year before the capture of that city the Turks built a fort of great strength on the European side of the Bosphorus, opposite the one which had long stood on the Asiatic side just at the narrowest point-about a mile wide--where the current is strong and navigation most difficult. And in this tower of Roumili Hissar, whose picturesque and massive ruins still guard the Straits, Mahomet II planted heavy cannon, at last made available through the services of a Hungarian founder, and forbade any vessel to pass without express permission. Constantinople, cut off from the east and practically shut off from the west, soon yielded to the assaults of a sultan who was also an engineer. The control of the Bosphorus by the cannon of Roumili Hissar became permanent.

The Genoese at Galata were at first granted privileges by the Turks similar to those they had enjoyed under the Greeks, and for a while they were allowed to pass the Turkish Bosphorus forts upon payment of a toll, but ships attempting to pass without halting were fired upon and sunk if they refused to stop. The Black Sea trade was thus brought to the verge of ruin. So long, however, as the Turks did not control the shores of the Black Sea as well as the Straits, they did not exclude all Christian shipping from the Straits. That control was not established until 1475, when, having already overrun the southern, western and eastern shores, the Turks took Azof and Crimea, reducing the Tartars to accepting their rule and ending the career of the old Genoese colony at Caffa. This made the Black Sea a Turkish lake, and, for the next three centuries, until the arrival of Russia in 1774, it was the settled policy of the Ottoman Empire to exclude all foreign ships from the "virgin waters" of the Euxine through the closure of the Bosphorus.