What was the first major naval victory of the Ottoman Empire against a European fleet?

The Battle of Zonchio was the Ottoman Empire’s first major naval victory against a European fleet.

Fought in August 1499 during the Ottoman–Venetian War, the battle pitted an Ottoman fleet commanded by Kemal Reis against a Venetian fleet led by Antonio Grimani near Cape Zonchio in the Ionian Sea. The engagement unfolded over four days—12, 20, 22, and 25 August—rather than as one brief clash.

The Ottoman victory helped establish the empire as a serious Mediterranean naval power. Ottoman forces soon captured Lepanto, and further successes during the war forced Venice to recognize significant Ottoman gains in the 1503 peace settlement. Zonchio is also known as the Battle of Sapienza or the First Battle of Lepanto.

It is often confused with Preveza, Djerba, or Lepanto. Those were important later victories: Preveza occurred in 1538, Djerba in 1560, and the famous Battle of Lepanto was an Ottoman defeat in 1571. Zonchio belongs to the earlier stage of Ottoman naval expansion.