In 1096, Tancred participated in First Crusade of of the Holy Lands. He was involved in the seige of Nicaea in 1097, in the capture of Tarsus and other cities and helped assisted in the seige of Antioch in 1098.
In July 1099, Tancred is claimed to be the first Crusader to enter the city of Jerusalem.
When the Kingdom of Jerusalem was established, Tancred became Prince of Galilee.