It was the stern logic of events which compelled the enterprise. Barbarous Turks swept westward. Arabia, Syria, the Isles of Greece, and, at last, in 1453, Constantinople itself, fell into their hands. The Eastern Empire, the last survival of the Empire of the Romans, perished beneath the sword of Mahomet. Then the pathway by land to Asia, to the fabled empires of Cathay and Cipango, was blocked by the Turkish conquest. Commerce, however, remained alert and enterprising, and men's minds soon turned to the hopes of a western passage which should provide a new route to the Indies. All the world knows the story of Christopher Columbus, his long years of hardship and discouragement; the supreme conviction which sustained him in his adversity; the final triumph which crowned his efforts. It is no detraction from the glory of Columbus to say that he was only one of many eager spirits occupied with new problems of discovery across the sea. Not the least of these were John and Sebastian Cabot, father and son. John Cabot, like Columbus, was a Genoese by birth; a long residence in Venice, however, earned for him in 1476 the citizenship of that republic. Like many in his time, he seems to have been both a scientific geographer and a practical sea-captain. At one time he made charts and maps for his livelihood. Seized with the fever for discovery, he is said to have begged in vain from the sovereigns of Spain and Portugal for help in a voyage to the West. About the time of the great discovery of Columbus in 1492, John Cabot arrived in Bristol. It may be that he took part in some of the voyages of the Bristol merchants, before the achievements of Columbus began to startle the world. At the close of the fifteenth century the town of Bristol enjoyed a pre-eminence which it has since lost. It stood second only to London as a British port. A group of wealthy merchants carried on from Bristol a lively trade with Iceland and the northern ports of Europe. The town was the chief centre for an important trade in codfish. Days of fasting were generally observed at that time; on these the eating of meat was forbidden by the church, and fish was consequently in great demand. The merchants of Bristol were keen traders, and were always seeking the further extension of their trade. Christopher Columbus himself is said to have made a voyage for the Bristol merchants to Iceland in 1477. There is even a tale that, before Columbus was known to fame, an expedition was equipped there in 1480 to seek the 'fabulous islands' of the Western Sea. Certain it is that the Spanish ambassador in England, whose business it was to keep his royal master informed of all that was being done by his rivals, wrote home in 1498: 'It is seven years since those of Bristol used to send out, every year, a fleet of two, three, or four caravels to go and search for the Isle of Brazil and the Seven Cities, according to the fancy of the Genoese.'