The Battle of Chaul was a naval battle between the Portuguese and an Egyptian Mamluk fleet in 1508 in the harbour of Chaul in India. The battle ended in a Mamluk victory. It followed the Siege of Cannanore (1507) in which a Portuguese garrison successfully resisted an attack by Southern Indian rulers. This was the first Portuguese defeat at sea in the Indian Ocean.

Previously, the Portuguese had been mainly active in Calicut, but the northern region of Gujarat was even more important for trade, and an essential intermediary in east–west trade: the Gujaratis were bringing spices from the Moluccas as well as silk from China, and then selling them to the Egyptians and Arabs.

The Portuguese' monopolizing interventions were however seriously disrupting Indian Ocean trade, threatening Arab as well as Venetian interests, as it became possible for the Portuguese to undersell the Venetians in the spice trade in Europe. Venice broke diplomatic relations with Portugal and started to look at ways to counter its intervention in the Indian Ocean, sending an ambassador to the Egyptian court. Venice negotiated for Egyptian tariffs to be lowered to facilitate competition with the Portuguese, and suggested that "rapid and secret remedies" be taken against the Portuguese. The sovereign of Calicut, the Zamorin, had also sent an ambassador asking for help against the Portuguese.

Coordinates: 18°32′46″N 72°55′38″E / 18.5461°N 72.9272°E / 18.5461; 72.9272 Chaul is a former city of Portuguese India, now in ruins. It is located 60 km south of Mumbai, in Raigad District of Maharashtra state in western India.

In 1508, the Egyptian Mamluks, allied with the Gujarat Sultanate vanquished the Portuguese in the Battle of Chaul. The first Portuguese settlement at Chaul took place in 1521 with the construction of the first fort on the south bank of the Kundalika River. In October 1531, the Portuguese erected a new square stone fortress, named Santa Maria do Castello, which contained a church and dwellings for 120 men. A town developed around the fortress, but a 1558 treaty precluded fortifying the town. The town was destroyed in a 1570-71 siege by the Nizam Shahi Sultan of Ahmadnagar, but a treaty was concluded which lifted the siege, and the town was rebuilt and surrounded by walls and bastions. A fort (Korlai fort) was built on the Morro de Chaul, a rocky promontory on the north side of the river opposite the town. The town withstood several further attacks, and its defense works were expanded in 1613.

Dom Francisco de Almeida (Portuguese pronunciation: [fɾɐ̃ˈsiʃku dɨ aɫˈmɐjðɐ]), also known as "the Great Dom Francisco" (born ca. 1450 at Lisbon; died March 1, 1510 at Table Bay, Cape of Good Hope), was a Portuguese nobleman, soldier and explorer. He distinguished himself as a counsellor to King John II of Portugal and later in the wars against the Moors and in the conquest of Granada in 1492. In 1503 he was appointed as the first governor and viceroy of the Portuguese State of India (Estado da Índia). Almeida is credited with establishing Portuguese hegemony in the Indian Ocean, with his victory at the naval Battle of Diu in 1509. Before Almeida could return to Portugal, he lost his life in 1510. His son Lourenço de Almeida too was killed in the Battle of Chaul in 1508.

As was customary for men in his social circle, he joined the military at a young age. In 1476 he took part in the Battle of Toro. He then fought in conflicts in different parts of Morocco and in 1492 participated in the Christian conquest of Granada on the side of the Castilians.^{[citation needed]}