The Battle of Mari, also called the Disaster of Mari, was a battle between the Mamluks of Egypt and the Armenians of Cilician Armenia on August 24, 1266.
The conflict started when the Mamluk Sultan Baibars summoned the Armenian ruler Hetoum I to abandon his allegiance to the Mongols, and accept himself as a suzerain, and remit to the Mamluks the territories and fortresses Hetoum has acquired through his alliance with the Mongols.
Following these threats, Hetoum I went to the Mongol court of the Il-Khan in Persia to obtain military support. During his absence however, the Mamluks marched on Cilician Armenia, led by Al-Mansur Ali and the Mamluk commander Qalawun.
Hetoum I's two sons, Leo (the future king Leo II) and Thoros led the defense by strongly manning the fortresses at the entrance of the Cilician territory. The Mamluks, however, overtook the forts by going through the mountains, and encountered the Armenians at Mari, near Darbsak on August 24, 1266, where the Armenians were defeated. Leo was made a prisoner, and Thoros was killed in action. The Armeno-Mongol son of the Constable Sempad, named Vasil Tatar, was also taken prisoner by the Mamluks and was taken into captivity with Leo, although they are reported to have been treated well.
Following their victory, the Mamluks invaded Cilicia, ravaging the three great cities of the Cilician plain: Mamistra, Adana and Tarsus, as well as the harbour of Ayas. Another group of Mamluks under Mansur took the capital of Sis. The pillage lasted 20 days, and 40,000 Armenians were made prisoners.
When Hetoum I arrived with Mongol troops, the country was already devastated. Hetoum I had to negotiate the return of his son Leo by giving control of Armenia's border fortresses to the Mamluks. In 1269, Hetoum I abdicated in favour of his son, and became a monk, but died a year later. Leo was left in the awkward situation of keeping Cilicia as a subject of the Mongol Empire, while at the same time he was paying tribute to the Mamluks.