He assisted in the siege of Antioch in 1098. One year later, during the assault on Jerusalem, Tancred, along with Gaston IV of Béarn, claimed to have been the first Crusader to enter the city on July 15. However, the first crusader to enter Jerusalem was Ludolf of Tournai, and he was followed by his brother Englebert. When the city fell, Tancred gave his banner to a group of the citizens who had fled to the roof of the Temple of Solomon. This should have assured their safety, but they were massacred, along with many others, during the sack of the city. The author of the "Gesta Francorum" (Deeds of the Franks) records that, when Tancred realised this, he was "greatly angered". When the Kingdom of Jerusalem was established, Tancred became Prince of Galilee.