Siege of Damietta (1218–19)

The Siege of Damietta of 1218 was part of the Fifth Crusade. The city, under the control of the Ayyubid Al-Kamil, was besieged by and taken by the Crusaders in 1219.

The knights laid siege to the Egyptian port city of Damietta with the aid of a Frisian fleet and a flotilla from the Republic of Genoa under father and son, Simone and Pietro Doria. One of the galleys was captained by the notorious pirate Alamanno da Costa. Even after being reinforced to 35,000 men however, the crusaders were heavily outnumbered by the 70,000 Muslims. In an interesting twist, the Crusaders formed an alliance with Kaykaus I of the Seljuk sultanate of Rum. Kaykaus attacked the Ayyubids in Syria so that the Crusaders wouldn't have to fight on two fronts.

...
Wikipedia