Siege of Diu The Siege of Diu occurred when an Ottoman imperial fleet attempted to capture the Indian city of Diu in 1538 , then held by the Portuguese . It ended with a Portuguese victory . Background . In the Indian Ocean , Süleyman Pasha , Governor of Egypt , led several naval campaigns against the Portuguese in an attempt to remove them and reestablish trade with India . In 1509 , the major Battle of Diu ( 1509 ) took place between the Portuguese and a joint fleet of the Sultan of Gujarat , the Mamlûk Burji Sultanate of Egypt , the Zamorin of Kozhikode with support of the Ottomans . Since 1517 , the Ottomans had attempted to combine forces with Gujarat in order to fight the Portuguese away from the Red Sea and in the area of India . Pro - Ottoman forces under Captain Hoca Sefer had been installed by Selman Reis in Diu . Diu in Gujerat , was with Surat , one of the main points of supply of spices to Ottoman Egypt at that time . However , Portuguese intervention thwarted that trade by controlling the traffic in the Red Sea . In 1530 , the Venetians could not obtain any supply of spices through Egypt . The Ottomans under the Governor of Yemen Mustafa , fought the Portuguese at Aden ( 1530 – 31 ) , and sent a fleet to Diu in Gujerat in order to repel a Portuguese siege of the city under Nuno da Cunha . The Portuguese retreated in February 1531 . Soon after however , the Sultan of Gujerat Bahadur Shah , who was under threat from the Mughal emperor Humayun made an agreement with the Portuguese , who took the opportunity to build a strong fort in front of Diu . The Portuguese seized the stronghold of Gogala ( Bender - i Türk ) near the city , and built the Diu Fort . Once the threat from Humayun was removed , Bahadur tried to negotiate the withdrawal of the Portuguese , but on 13 February 1537 he died drowning during the negotiations on board a Portuguese ship in unclear circumstances , both sides blaming the other for the tragedy . Bahadur Shah had also appealed to the Ottomans to expel the Portuguese , which led to the 1538 expedition . 1538 Siege of Diu . The Ottoman governor of Egypt since 1525 , Süleyman Pasha , obtained an agreement from Istanbul to launch an attack against the Portuguese . A fleet of 80 ships , including 17 galley s and 2 galleon s , was prepared , and the building of a canal was started between the Nile and Suez in 1531 - 1532 . There were delays however due to the Siege of Coron in the Mediterranean , and the Ottoman - Safavid war of 1533 - 1535 . Meanwhile , the Portuguese continued their progression , and killed Bahadur Shah in February 1537 . Aden in Yemen was captured by the Ottomans under Süleyman Pasha in 1538 , in order to provide an Ottoman base for raids against Portuguese possessions on the western coast of India . The Sultan of Aden , Sheikh Amir bin Dawaud , an ally of the Portuguese , was hanged when he was invited on the Ottoman ships , and the city was captured without a siege . The Ottoman fleet , consisting of 72 ships , left Aden on 19 August 1538 and arrived at Diu on 4 September 1538 . It was the largest Ottoman fleet ever sent into the Indian Ocean . The Ottoman fleet laid siege to Diu with 130 cannons and bombarded the city . Soon however , news were received of the arrival of a strong Portuguese relief fleet . At the same time , it seems that the new ruler of Gujerat was weary of Ottoman control , and did not support them adequately during the siege . The Ottomans finally had to lift the siege . Aftermath . After the failed siege , the Ottomans returned to Aden , where they fortified the city with 100 pieces of artillery . One of them is still visible today at the Tower of London , following the capture of Aden by British forces in 1839 . Süleyman Pasha also established Ottoman suzerainty over Shihr and Zabid , and reorganized the territories of Yemen and Aden as an Ottoman province , or Beylerbey lik . Süleyman Pasha intended to launch a second expedition against the Portuguese in Diu , but this did not happen . In 1540 , the Portuguese sent a retaliatory expedition to the Red Sea , attacking Suakin and Kusayr , and attempted to take Suez with a fleet of 72 ships in 1541 . In 1546 , the Ottoman established a new naval base in Basra , thus threatening the Portuguese in Hormuz . The Ottomans would suffer a strong naval defeat against the Portuguese in the Persian Gulf in 1554 . Further conflict between the Ottomans and the Portuguese would lead to the Ottoman expedition to Aceh in 1565 . The Indians would not retake possession of the Diu enclave until Operation Vijay in 1961 .