Arnala Fort is built on a small island off the port town of Arnala, located around 13 km (8 miles) north of Bassein, Maharashtra, India. Being an island fort, it is also called Jaldurg or Janjire-Arnala. The Portuguese, who built the present fort, called the island Ilha das Vacas (Island of Cows). History The island of Arnala, which has water on all four sides, belonged to Sultan Mahmud Begda of Gujarat. The island was conquered by the Portuguese in 1530. In 1737, after nearly two hundred years of Portuguese rule, the fort came under the control of the Marathas in 1737. The fort was rebuilt by the first Bajirao. In the middle of 1817, the fort came under the control of the British In 1516 a local chieftain in Gujarat, Sultan Mahmud Begda, constructed the fort on the island, strategically located at the mouth of the Vaitarna river. In the 1530s the Portuguese had established their operations in the coastal area, headquartered at Fort Bassein, and soon gained control of the island. The Portuguese captain of Bassein donated the island to a Portuguese nobleman who tore down the old fort and began construction of a fort. The nobleman never completed the fort. Still, it remained under Portuguese control for two centuries; they used it to control shipping and navigation along the northern Konkan coast. During the late 17th and early 18th centuries, after a long struggle with the Mughal Empire, the Maratha Confederacy came to dominate the region. In 1737 the then Peshwa Baji Rao I sent his brother, Chimaji Appa, to take the Bassein Fort from the Portuguese. After winning the Battle of Vasai, his general, Shankarji Pant, persuaded Chimaji to launch an assault on Fort Arnala, for its strategic importance to the Maratha navy in assaulting Portuguese interests. Their first assault, coordinated with a Maratha naval force commanded by Govindji kasar & Manaji Agre, was routed by a superior Portuguese naval force. A second assault on the fort on 28 March 1737, caught the Portuguese by surprise and forced them to abandon the fort. The victory was commemorated by a plaque installed on the northern wall of the fort and is still visible today. The Marathas then rebuilt the fort, constructing three bastions Bahirav, Bhavani, and Bava. The British captured the fort on 18 January 1781 during the First Anglo-Maratha War. The Treaty of Salbai nominally returned the