The first great obstacle on the Crusaders' path was Nicaea, the Seljuk capital, prompting the Siege of Nicaea in 1097. Boutoumites had been instructed by Alexios to secure the surrender of the city to imperial forces, and not to the Crusaders. Already from the outset of the siege, Boutoumites, through numerous letters, tried to entice the Seljuks to surrender to him, whether through promises of amnesty or threats of a wholesale massacre should the Crusaders capture the city by force. The Turks had entered negotiations, allowing Boutoumites to enter the city. Two days later, at the news of the approach of a relief force under Sultan Kilij Arslan I (r. 1092–1107), they forced him to leave. After the relief force was defeated by the Crusaders, however, and as an imperial squadron under Boutoumites gained control of the city's open supply route through the Ascanian Lake and 2,000 Byzantines under Tatikios joined the Crusaders in the siege, the city's inhabitants determined to accept Alexios's terms: Boutoumites entered Nicaea and showed them the Byzantine emperor's chrysobull, offering generous terms and honours for the Sultan's wife and sister, who were in the city. Boutoumites, however, kept the deal a secret, and arranged with Tatikios for a renewed assault by the Crusaders and Tatikios's men, in which the city would ostensibly be captured by the Byzantines. The ruse worked: the day of the final assault was set for June 19, but when the assault began at dawn, the Byzantines, allowed in through the lake-ward gates, raised their standards on the battlements, leaving the Crusaders outside.