The Portuguese on the island of Mombasa, off present-day Kenya, have for many years dominated the gold and slave trade on the eastern coast of Africa.

The natives of Mombasa in 1652 had asked the sultan of Oman on the Arabian peninsula for help in expelling the Portuguese; he had sent a fleet that raided the Portuguese-held island of Zanzibar to the south of Mombasa.

This was the start of a long struggle between the Omanis, who are Arab Muslims, and the Portuguese, who are European Christians, for control of the East African coast, its natural resources, and the profitable African slave trade.

A former king of Pate (an island off Kenya) in 1687 appeals to the Portuguese for help in regaining his kingdom from the Omanis.

The Portuguese fleet on arrival at Pate finds a stronger Omani fleet waiting and is forced to retreat to Mombasa to the south.