The fourth Ottoman-Portuguese Conflicts (1580–1589) was an armed military conflict between the Portuguese Empire against the Ottoman Empire and the Ajuran Empire, in the Indian Ocean.
The Ottoman Navy, from 1580 to 1584 for the first time attacked only the Portuguese ships in the Indian Ocean. In 1585 Mir Ali Bey successfully repelled a Portuguese attempt to capture harbors controlled by the Somalis in the Horn of Africa (Barawa, Jumbo and Mogadishu) but failed to do so.
In 1586 the Portuguese army repelled the Ottomans in Kilifi, Patta and Melinde.
Mombasa was seized by the Ottomans, but the African tribe of Zimba joined the Portuguese and retook the city. The city lost most of her population during the massacre that followed her fall, and had to be rebuilt and repopulated by the Portuguese.
In 30 January 1589, a Portuguese fleet sent from Goa in Portuguese India, with two galleass, five galleys, six galliots, seven other ships and with 900 soldiers, was able to recapture the lost cities and capture the Turkish admiral, Mir Ali Bey.