Bengal Sultanate–Delhi Sultanate War

The Bengal Sultanate–Delhi Sultanate War was a conflict between the Bengal Sultanate and the Delhi Sultanate in the Indian subcontinent. The war resulted in Delhi recognizing the separation of Bengal from its authority.

Background
In the early 14th century, Delhi's rebel governors in Bengal formed their own sultanates. By 1352, Shamsuddin Ilyas Shah defeated other rulers in Bengal and united the region into one sultanate. Ilyas Shah proclaimed himself as the Sultan of Bengal. Ilyas Shah's earlier military campaigns also involved the sacking of Kathmandu and Varanasi; and an invasion of Orissa.

Location
The conflict centered on the mud fort of Ekdala. The fort was located on an island surrounded by a moat and marshy jungle. The exact location of the area is unclear; with various sources saying it may have been in Dinajpur, Dhaka or Pandua.

Siege of Ekdala (1353)
Firuz Shah Tughluq, the Delhi sultan, led his army and navy into Bengal in 1353. Ilyas Shah's forces deserted the capital Lakhnauti and took shelter in the Ekdala fort. The Delhi army then besieged the fort, but was deterred by its island location and the Bengal navy. The Delhi army occupied Lakhnauti and issued a proclamation asking locals to pledge allegiance to Delhi. According to erstwhile Delhi accounts, the Bengal and Delhi forces engaged in a battle after the Delhi Sultan tricked Ilyas Shah into attacking Delhi forces, who pretended to withdraw. The conflict was settled after Bengal agreed to pay an annual tribute to Delhi, according to erstwhile Delhi accounts. R. C. Majumdar, a leading modern Indian historian, believed that the exchange of gifts between Delhi and Bengal indicated each others' sovereignty.

Siege of Ekdala (1359)
Firuz Shah Tughluq again invaded Bengal in 1359 when Ilyas Shah's successor Sikandar Shah took the throne. Tughluq felt Sikandar Shah had violated the terms of the treaty reached with his father. Tughluq sought to place the son-in-law of one of Ilyas Shah's rivals as the sultan of Bengal. During the invasion, Sikandar Shah based himself in Ekdala fort like his father. Bengal also received support from Rajendra Choda II, a South Indian ruler.

The Delhi army besieged the island fort for months. After growing exhausted of Bengal's climate, the Delhi Sultan reached a peace treaty with Sikandar Shah. Delhi recognized Sikandar as an independent ruler. The peace treaty ensured Bengal's independence for two centuries.