In August–October 1821, after the outbreak of the Greek War of Independence, he commanded the Egyptian squadron that joined the fleet of Nasuhzade Ali Pasha. After relieving Patras, on 1 October, Ali sent Ismael Gibraltar into the Gulf of Corinth, where he destroyed the commercial port of Galaxeidi; 34 vessels were captured and the rest of the town's fleet, the largest in western Greece, burned.
In 1824, he was placed by the ruler of Egypt, Muhammad Ali, in command of a fleet of three frigates and ten sloops, with some 3,000 Albanian troops, to capture the island of Kasos, whose inhabitants had been raiding Ottoman shipping during the previous years. The Egyptian force landed on 19 June 1824, catching the Kasiots completely unaware. For only 30 casualties among the Albanians, the island was plundered and destroyed: 500 men were slain, and over 2,000 women and children were enslaved.
He acted as an emissary of Muhammad Ali, for whom he completed diplomatic missions in England, Sweden, Germany, and Italy.
He died in a military encounter with the Greeks in 1826.
- Finlay, George (1861). History of the Greek Revolution, Vol. I. Edinburgh and London: William Blackwood and Sons. pp. 272–273.
- Finlay, George (1861). History of the Greek Revolution, Vol. II. Edinburgh and London: William Blackwood and Sons. pp. 47–48.
- Minutoli, Barness von. (1827) Recollections of Egypt: With a Portrait of Mahomet Ali Pacha. Philadelphia: Carey, Lea and Carey. pp. 216-218.
- "Ismael Gibraltar", The Gentleman's Magazine, Vol. 96, Part 2, August 1826, p. 186.