In 1097, the Crusader armies assembled at Constantinople having traveled in groups eastward through Europe. Alexios I, who had requested only some western knights to serve as mercenaries to help fight the Seljuk Turks, blockaded these armies in the city and would not permit them to leave until their leaders swore oaths promising to restore to the Empire any land formerly belonging to it that they might conquer on the way to Jerusalem. The Crusaders eventually swore these oaths, individually rather than as a group. In return, Alexios gave them guides and a military escort. The Crusaders were however exasperated by Byzantine tactics, such as negotiating the surrender of Nicaea from the Seljuks while it was still under siege by the Crusaders, who hoped to plunder it to help finance their journey. The Crusaders, feeling betrayed by Alexios, who was able to recover a number of important cities and islands, and in fact much of western Asia Minor, continued on their way without Byzantine aid. In 1098, when Antioch had been captured after a long siege and the Crusaders were in turn themselves besieged in the city, Alexios marched out to meet them, but, hearing from Stephen of Blois that the situation was hopeless, he returned to Constantinople. The Crusaders, who had unexpectedly withstood the siege, believed Alexios had abandoned them and considered the Byzantines completely untrustworthy. Therefore, they regarded their oaths as invalidated.