Genoa started expanding during the First Crusade. In 1097 Hugh of Châteauneuf, Bishop of Grenoble and William, Bishop of Orange, went to Genoa and preached in the church of San Siro in order to gather troops for the First Crusade. At the time the city had a population of about 10,000. Twelve galleys, one ship and 1,200 soldiers from Genoa joined the crusade. The Genoese troops, led by noblemen de Insula and Avvocato, set sail in July 1097. The Genoese fleet transported and provided naval support to the crusaders, mainly during the siege of Antioch in 1098, when the Genoese fleet blockaded the city while the troops provided support during the siege. In the siege of Jerusalem in 1099 Genoese crossbowmen led by Guglielmo Embriaco acted as support units against the defenders of the city.