Cannon were beginning to be used in sieges, but stone balls were used in the larger pieces of artillery; and the larger the gun, the greater was the effect it was expected to produce. Even in Constantinople there was some artillery too large to be of much use, as the land wall had not been constructed to admit of their recoil, and the ramparts were so weak as to be shaken by their concussion. Constantine had also only a moderate supply of gunpowder. The machines of a past epoch in military science, but to the use of which the Greeks adhered with their conservative prejudices, were brought from the storehouses, and planted on the walls beside the modern artillery. Johann Grant, a German officer, was the most experienced artilleryman and military engineer in the place. 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.