Siege of Nicaea The Siege of Nicaea took place from May 14 to June 19 , 1097 , during the First Crusade . Background . Nicaea ( İznik ) , located on the eastern shore of Lake İznik , had been captured from the Byzantine Empire by the Seljuk Turks in 1081 , and formed the capital of the Sultanate of Rüm . In 1096 , the People ' s Crusade , the first stage of the First Crusade , had plundered the land surrounding the city , before being destroyed by the Turks . As a result , Sultan Kilij Arslan I initially felt that the second wave of crusade rs were not a threat . He left his family and his treasury behind in Nicaea and went east to fight the Danishmends for control of the Melitene . Crusader siege . The crusaders began to leave Constantinople at the end of April 1097 . Godfrey of Bouillon was the first to arrive at Nicaea , with Bohemund of Taranto , Bohemond ' s nephew Tancred , Raymond IV of Toulouse , and Robert II of Flanders following him , along with Peter the Hermit and some of the survivors of the People ' s Crusade , and a small Byzantine force under Manuel Boutoumites . They arrived on May 6 , severely short on food , but Bohemund arranged for food to be brought by land and by sea . They put the city to siege beginning on May 14 , assigning their forces to different sections of the walls , which were well - defended with 200 towers . Bohemund camped on the north side of the city , Godfrey on the east , and Raymond and Adhemar of Le Puy on the south . Defeat of Kilij Arslan . On May 16 , the Turkish defenders sallied out to attack the crusaders , but the Turks were defeated in a skirmish with the loss of 200 men . The Turks sent messages to Kilij Arslan begging him to return , and when he realized the strength of the crusaders he quickly turned back . An advance party was defeated by troops under Raymond and Robert of Flanders on May 20 , and on May 21 , the crusader army defeated Kilij in a pitched battle which lasted long into the night . Losses were heavy on both sides but in the end the Sultan retreated , despite the pleas of the Nicaean Turks . The rest of the crusaders arrived throughout the rest of May , with Robert Curthose ( accompanied by Ralph de Guader ) and Stephen of Blois arriving at the beginning of June . Meanwhile Raymond and Adhemar built a large siege engine , which was rolled up to the Gonatas Tower in order to engage the defenders on the walls while miners mined the tower from below . The tower was damaged but no further progress was made . Byzantine arrival . Byzantine emperor Alexius I chose not to accompany the crusaders , but marched out behind them and made his camp at nearby Pelecanum . From there , he sent boats , rolled over the land , to help the crusaders blockade Lake Ascanius , which had up to this point been used by the Turks to supply Nicaea with food . The boats arrived on June 17 , under the command of Manuel Boutoumites . The general Tatikios was also sent , with 2 , 000 foot soldiers . Alexius had instructed Boutoumites to secretly negotiate the surrender of the city without the crusaders ' knowledge . Tatikios was instructed to join with the crusaders and make a direct assault on the walls , while Boutoumites would pretend to do the same to make it look as if the Byzantines had captured the city in battle . This was done , and on June 19 the Turks surrendered to Boutoumites . When the crusaders ' discovered what Alexius had done , they were quite angry , as they had hoped to plunder the city for money and supplies . Boutoumites , however , was named " dux " of Nicaea and forbade the crusaders from entering in groups larger than 10 men at a time . Boutoumites also expelled the Turkish generals , whom he considered just as untrustworthy ( and indeed , these men tried to take their Byzantine guides hostage on their way to meet with the emperor ) . Kilij Arslan ' s family went to Constantinople and were eventually released without ransom . Alexius gave the crusaders money , horses , and other gifts , but the crusaders were not pleased with this , believing they could have had even more if they had captured Nicaea themselves . Boutoumites would not permit them to leave until they had all sworn an oath of vassalage to Alexius , if they had not yet done so in Constantinople . As he had in Constantinople , Tancred at first refused , but he eventually gave in . Aftermath . The crusaders left Nicaea on June 26 , in two contingents : Bohemond , Tancred , Robert of Flanders , and Taticius in the vanguard , and Godfrey , Baldwin of Boulogne , Stephen , and Hugh of Vermandois in the rear . Taticius was instructed to ensure the return of captured cities to the empire . Their spirits were high , and Stephen wrote to his wife Adela that they expected to be in Jerusalem in five weeks . On July 1 , they defeated Kilij at the Battle of Dorylaeum , and by October they reached Antioch ; they would not reach Jerusalem until two years after leaving Nicaea .