The Siege of Damietta of 1218 was part of the Fifth Crusade

Fifth Crusade

The Fifth Crusade was an attempt to reacquire Jerusalem and the rest of the Holy Land by first conquering the powerful Ayyubid state in Egypt....

. The city, under the control of the Ayyubid Al-Kamil

Al-Kamil

Al-Kamil was a Kurdish Ayyubid sultan who ruled North Africa. During his tenure as sultan, the Ayyubids defeated two crusades. In a temporary agreement with the Crusaders, he ceded Jerusalem to the Christians.-Biography:He was the son of sultan al-Adil, a brother of Saladin...

, was besieged by and taken by the Crusaders in 1219.

The knights lay siege to the city of Damietta

Damietta

Damietta , also known as Damiata, or Domyat, is a port and the capital of the Damietta Governorate in Egypt. It is located at the intersection between the Mediterranean Sea and the Nile, about north of Cairo.-History:...

 with the aid of a Frisian fleet

Frisian participation in the Crusades

Frisian participation in the Crusades is attested from the very beginning of the First Crusade, but their presence is only felt substantially during the Fifth Crusade. They participated in almost all the major Crusades and the Reconquista...

 and a flotilla from the Republic of Genoa

Republic of Genoa

The Most Serene Republic of Genoa |Ligurian]]: Repúbrica de Zêna) was an independent state from 1005 to 1797 in Liguria on the northwestern Italian coast, as well as Corsica from 1347 to 1768, and numerous other territories throughout the Mediterranean....

 under father and son Simone

Simone Doria (admiral)

Simone or Simon Doria was a Genoese merchant, politician, and admiral, a member of the powerful Doria family. He was the son of Ansaldo Doria and Anna Grimaldi. He was elected consul six times between 1175 and 1188. Having been elected admiral in 1189, he led a naval fleet in support of the troops...

 and Pietro Doria. Even after reinforced to 35,000 men however, they were heavily outnumbered by the 70,000 Muslims. In an interesting twist, the Crusaders formed an alliance with Kay Kaus I, Seljuk

Seljuq dynasty

The Seljuq ; were a Turco-Persian Sunni Muslim dynasty that ruled parts of Central Asia and the Middle East from the 11th to 14th centuries...

 Sultanate of Rum

Sultanate of Rûm

The Sultanate of Rum , also known as the Anatolian Seljuk State , was a Turkic state centered in in Anatolia, with capitals first at İznik and then at Konya. Since the court of the sultanate was highly mobile, cities like Kayseri and Sivas also functioned at times as capitals...

 in Anatolia

Anatolia

Anatolia is a geographic and historical term denoting the westernmost protrusion of Asia, comprising the majority of the Republic of Turkey...

. Kaus attacks the Ayyubids in Syria

Syria

Syria , officially the Syrian Arab Republic , is a country in Western Asia, bordering Lebanon and the Mediterranean Sea to the West, Turkey to the north, Iraq to the east, Jordan to the south, and Israel to the southwest....

so that the Crusaders wouldn't have to fight on two fronts.