Damietta (Arabic: دمياط‎ Dumyāṭ), 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 200 kilometres (120 mi) north of Cairo.

In Ancient Egypt, the city was known as Tamiat, but it became less important in the Hellenic period after the construction of Alexandria.

The Abbasids used Alexandria, Damietta, Aden and Siraf as entry ports to India and the Tang Empire of China. Damietta was an important naval base during the Abbasid, Tulunid and Fatimid periods. This led to several attacks by the Byzantine Empire, most notably the sack and destruction of the city in May 853.

Damietta was again important in the 12th and 13th centuries during the time of the Crusades. In 1169, a fleet from the Kingdom of Jerusalem, with support from the Byzantine Empire, attacked the port, but it was defeated by Saladin.

During preparations for the Fifth Crusade in 1217, it was decided that Damietta should be the focus of attack. Control of Damietta meant control of the Nile, and from there the crusaders believed they would be able to conquer Egypt. From Egypt they could then attack Palestine and recapture Jerusalem. When the port was besieged and occupied by Frisian crusaders in 1219, Francis of Assisi arrived to peaceably negotiate with the Muslim ruler. The siege devastated the population of Damietta. In October 1218 reinforcements arrived including the Legate Pelagius with the English earls Ranulf of Chester, Saer of Winchester, and William Aubigny of Arundel together with Odonel Aubigny, Robert Fitzwalter, John Lacy of Chester, William Harcourt and Oliver the illegitimate son of King John. In 1221 the Crusaders attempted to march to Cairo, but were destroyed by the combination of nature and Muslim defenses.