A considerable number of Italians hastened to Constantinople as soon as they heard of its danger, eager to defend so important a depot of Eastern commerce.  The spirit of enterprise and the love of military renown had become as much a characteristic of the merchant nobles of the commercial republics as they had been, in a preceding age, distinctions of the barons in feudal monarchies.  All the nations who then traded with Constantinople furnished contingents to defend its walls.  A short time before the siege commenced, John Justiniani arrived with two Genoese galleys and three hundred chosen troops, and the Emperor valued his services so highly that he was appointed general of the guard.  The resident bailo of the Venetians furnished three large galeases and a body of troops for the defence of the port.  The consul of Catalans, with his countrymen and the Aragonese, undertook the defence of the great palace of Bukoleon and the port of Kontoskalion.  Cardinal Isidore, with the papal troops, defended the Kynegesion, and the angle of the city at the head of the port down to St. Demetrius.  The importance of the aid which was afforded by the Latins is proved by the fact that of twelve military divisions, into which Constantine divided the fortifications, the commands of only two were intrusted to the exclusive direction of Greek officers.  In the others, Greeks shared the command with foreigners, or aliens alone conducted the defence.

When all Constantine’s preparations for defence were completed, he found himself obliged to man a line of wall on the land side of about five miles in length, every point of which was exposed to a direct attack.  The remainder of the wall toward the port and the Propontis exceeded nine miles in extent, and his whole garrison hardly amounted to nine thousand men.  His fleet consisted of only twenty galleys and three Venetian galeases, but the entry of the port was closed by a chain, the end of which, on the side of Galata, was secured in a strong fort of which the Greeks kept possession.  During the winter the Emperor sent out his fleet to ravage the coast of the Propontis as far as Cyzicus, and the spirit of the Greeks was roused by the booty they made in these expeditions.

Mahomet II spent the winter at Adrianople, preparing everything necessary for commencing the siege with vigor.  His whole mind was absorbed by the glory of conquering the Roman Empire and gaining possession of Constantinople, which for more than eleven hundred fifty years had been the capital of the East.  While the fever of ambition inflamed his soul, his cooler judgment also warned him that the Ottoman power rested on a perilous basis as long as Constantinople, the true capital of his empire, remained in the hands of others.  Mahomet could easily assemble a sufficient number of troops for his enterprise, but it required all his activity and power to collect the requisite supplies of provisions and stores for the immense military and naval force he had ordered to assemble, and to prepare the artillery and ammunition necessary to insure success.