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 lay siege to the 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 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 Kay Kaus I, Seljuk Sultanate of Rum in Anatolia. Kaus attacks the Ayyubids in Syria so that the Crusaders wouldn't have to fight on two fronts.