The second Ottoman-Portuguese War (1538–1557) was an armed military conflict between the Portuguese Empire and Ethiopian Empire against the Ottoman Empire, Ajuran Sultanate, and Adal Sultanate, into the Horn of Africa, the Indian Ocean, the Red Sea and in East Africa.
This war took place upon the backdrop of the Ethiopian-Adal War. Ethiopia had been invaded in 1529 by the Somali Imam Ahmed Gargn. Portuguese help, which was first asked by Emperor Lebna Dengel in 1520 to help defeat Adal while it was weak, finally arrived in Mitsiwa on February 10, 1541, during the reign of Emperor Galawdewos. The force was led by Cristóvão da Gama (second son of Vasco da Gama) and included 400 musketeers and few Portuguese cavalry as well as a number of artisans and other non-combatants.
An Ottoman legion (musketeers, and some guns) had already been fighting alongside the Somali army for some time, and with the arrival of the Portuguese, the Ottomans sent reinforcements: 2000 Arabian musketeer, 900 Turkish pikemen, 1000 Turkish foot musketeers, some Shqiptar foot soldiers (with muskets) and Turkish horsemen.
Major hostilities between Portugal and the Ottoman Empire began in 1538, where the Ottomans with 54 ships laid siege to Diu, which had been built by the Portuguese in 1535. The Ottoman fleet was led by Suleiman I's emissary Hussein Pasa, but the attack was not successful and the siege was lifted.
The Portuguese under Estêvão da Gama (first son of Vasco da Gama) attacked the Ottoman fleet near Suez Harbor, leaving Goa on December 31, 1540 and reaching Aden January 27, 1541. The fleet reached Massawa on February 12, where Gama left a number of ships and continued north. Reaching Suez, he discovered that the Ottomans had long known of his raid, and foiled his attempt to burn the beached ships. Gama was forced to retrace his steps to Massawa, although pausing to attack the port of El-Tor (Sinai Peninsula).
On February, 1542, in his first encounter with the Somali-Ottoman forces at the Battle of Baçente, Cristóvão da Gama was able to soundly defeat an Ottoman and Somali contingent. The Portuguese were again victorious at the Battle of Jarte. However, in the Battle of Wofla, Somali and Ottoman forces were victorious and Gama was captured and killed upon his refusal to convert to Islam.
Gelawdewos was eventually able to reorganize his forces and absorb the remaining Portuguese soldiers and defeated Gragn (who was killed) at the Battle of Wayna Daga, marking the end of the war (although warfare would resume not long after, at a much diminished scale).
Diu repeatedly became a focal point of Portuguese and Ottoman naval combat and the Portuguese navy several times defeated the Ottoman fleet near Diu (1541, 1546, 1549).
Elsewhere in the Indian Ocean naval combat was also intense. In 1547 the Admiral Piri Reis took command of the Ottoman-Egyptian fleet in the Indian Ocean and on 26 February 1548 recaptured Aden, in 1552 Bandar Abbas and Masqat (Muscat). Turning further east, Piri failed to capture Hormuz, at the entrance of the Persian Gulf. The Portuguese were also able to successfully defend Bahrain, and in 1556 the Ottoman fleet was destroyed by a storm near Gujarat.
In 1557, however, after the (nominal only) declaration of a province of Habesh ("Abyssinia", i.e. Ethiopia), Ottoman forces invaded Ethiopia and were able to capture the important port of Massawa, beginning the Ethiopian-Ottoman War.