By 1101, the Crusaders had controlled the southern ports including Jaffa, Haifa, Arsuf and Caesarea, hence they managed to cut off the northern ports including Beirut from Fatimid support by land. In addition, the Fatimids had to disperse their forces including 2,000 soldiers and 20 ships in each of the remaining ports, until the main support could arrive from Egypt. Beginning on 15 February 1102, the Crusaders began harassing Beirut, until the Fatimid army arrived in early May.

In late autumn 1102, ships carrying Christian pilgrims to the Holy Land were forced by storm to land in the vicinity of Ascalon, Sidon and Tyre. The pilgrims were either slain or taken as slaves to Egypt. Hence, controlling the ports became urgent for the safety of pilgrims, in addition to the arrival of men and supply from Europe.

The siege of Beirut was an event in the aftermath of the First Crusade. The coastal city of Beirut was captured from the Fatimids by the forces of Baldwin I of Jerusalem on 13 May 1110, with the assistance of Bertrand of Toulouse and a Genoese fleet.