The Portuguese had eighteen ships commanded by the Viceroy, with about 1,500 Portuguese soldiers and 400 local combatants from
Cochin. The Allied side had one hundred ships, but only twelve were major vessels; the rest were small shallow-draught craft. After detecting the Portuguese, who approached from Cochin to the north, and fearing their technical superiority, the
Egyptians decided to take advantage of the port of
Diu and its fort, which had its own artillery. It was therefore decided to stay anchored at the port and await an attack from the Portuguese. This may also have been due to the training of the
Egyptians, who were used to the more sheltered bays in the
Mediterranean. There they also relied upon land-based
artillery reinforcements to defeat the enemy. The Portuguese started the battle with a massive naval bombardment using their on board artillery, followed by hand-to-hand combat in the
harbour of
Diu.
These Portuguese ships had guns of greater caliber, better
artillery crews, and were better manned and better built. The Portuguese
naval infantry also had an advantage over the
Egyptian Mamluks, not only because they were heavily armed and equipped (armour,
arquebuses and a type of grenade made of clay with gunpowder inside), but also because they were seasoned professional seamen.
The tough state-of-the art multi-rigged Portuguese
carracks and smaller fast
caravels had been developed over the previous decades to cope with the storms of the
Atlantic Ocean and were bristling with cannons. The smaller Indian Ocean
dhows and Mediterranean-type
galleys launched by the coalition of the
Samoothiri Raja,
Gujarat and
Egypt were no match. The Portuguese ships were able to shoot their powerful cannons and thus dissuade the smaller craft from coming near them. Even when they did come near, the smaller galleys and dhows were low in the water, and so unable to board the Portuguese ships, while being sprayed from above with small arms, grenades and smaller caliber cannon.