In 1824, after the conquest of Psara by the Turks, he commanded the Greek forces which prevented the further progress of the Sultan's fleet, though at the cost of the loss of many fire ships and men to themselves.
The fleets passed on opposite tacks, and the Dutch tried to destroy their enemy with fire-ships without success.
On the 28th of May Rupert and d'Estrees, believing that De Ruyter was too much afraid of their superior numbers to venture to sea, sent in a squadron of light vessels and fire-ships to attack him, but he took the offensive at once, scattering the light squadron, and falling with energy on the restof the fleet, which, not being in expectation of a vigorous assault, was taken at a disadvantage.
Spain, unable to defend its possessions singlehanded, appealed to the Dutch for naval help. In September 1675 De Ruyter was sent into the Mediterranean with 18 sail of the line and four fire-ships.
Khosrev, too, emboldened by this new sense of support, ventured to sea, surprised and destroyed Psara (July 2), and planned an attack on Samos, which was defeated by Miaoulis and his fire-ships (August 16, 17).