The city existed under the Phrygians but may have been much older. It was a Roman trading post, and a bishopric under the Byzantine Empire. After the Battle of Manzikert in 1071 it was taken by the Seljuk Turks.
Dorylaeum was the site of the first major victory for the Crusaders during the First Crusade. The Crusaders had left Nicaea with a deep distrust of the Byzantines, who had taken the city without their knowledge after a long siege. Without Byzantine guides they were vulnerable to ambushes by the Turks, so they split into two groups, led by Bohemond of Taranto and Godfrey of Bouillon. Bohemond's force was surrounded outside Dorylaeum by Kilij Arslan I at the end of June, 1097. On July 1 the Turkish archers attacked, charging in, firing their arrows, and quickly retreating before the Crusaders could counterattack. The archers did little damage to the heavily armoured knights, but they inflicting heavy casualties on the horses and unarmoured foot soldiers.
Later in the morning Godfrey of Bouillon arrived, after receiving a message from Bohemond. Godfrey broke through the Turkish ranks, but was then surrounded as well. As Godfrey and Bohemond defended themselves against the archers, Adhemar of Le Puy's force arrived. Instead of attempting to break the Turkish ranks as Godfrey had done, Adhemar avoided the archers and captured the Turkish camp. The Turks panicked and Kilij Arslan could not prevent them from retreating. The camp and the city were plundered, allowing the Crusaders to replenish their supplies. The victory also allowed the Crusaders to march virtually unopposed through Anatolia on their way to Antioch.
A second battle took place at Dorylaeum on October 25, 1147, during the Second Crusade. Conrad III, running out of provisions, stopped there to rest, and his army was annihilated by the Turks. The Germans were unable to continue the Crusade, and Conrad made his way to the army led by Louis VII of France, although the Crusade eventually failed completely.