In 1658, Ottoman power was redirected north in a campaign against George II Rákóczi, Prince of Transylvania, which evolved into a long conflict with the Habsburgs. For the next few years, the Venetian fleet, again under the command of Morosini, unsuccessfully attempted to maintain the blockade of the Straits of the Dardanelles. Morosini also resumed his tactic of attacking Ottoman strongholds: a siege of the island of Santa Maura (Lefkada) in August 1658 failed, but in 1659, the Venetians, aided by the Maniots, sacked Kalamata in the Peloponnese, followed by Torone in the Chalcidice, Karystos in Euboea, and Çeşme. However, since Venice could not spare forces to occupy these places, these raids gained the Republic nothing of substance. On the Ottoman side, Köprülü Mehmed ordered the construction of two new forts, Sedd el Bahr ("Rampart of the Sea") and Kilid Bahr ("Key of the Sea"), at the European shore of the entrance of the Dardanelles, to prohibit the Venetians from entering the Straits again.
In the meantime, war-weariness had set in among the Venetians, who suffered from the disruption in trade. Peace feelers were sent to the Ottomans, but their demand for the full concession of Crete as a condition for peace was unacceptable to the Republic. With the end of the war between France and Spain however, the Venetians became encouraged, hoping to receive increased assistance in money and men, especially from the French, whose traditionally good relations with the Porte had soured of late.
This support did indeed soon develop, when individuals or whole companies of men from across Western Europe volunteered for the Republic's army, while Christian rulers also felt obliged to provide men, supplies and ships. The first French contingent of 4,200 men under Prince Almerigo d'Este arrived in April 1660, along with further contingents of German mercenaries, troops from Savoy, and Maltese, Tuscan and French ships. Despite this increase in strength, Morosini's operations in 1660 were a failure: an assault on Canea in August succeeded in taking the outlying fortifications but failed to retake the city itself; similarly, an attack against the Ottoman siege lines at Candia in September achieved some success, but did not break the Ottoman siege. Following the death of Prince d'Este at Naxos shortly after, the French contingent returned home, followed soon after by a disheartened Morosini, who was succeeded by his kinsman Giorgio. In 1661, Giorgio Morosini scored a few minor successes: he broke an Ottoman blockade of Tinos, and, pursuing the Ottoman fleet, defeated it off Milos. The next few years however were relatively idle. Although the Ottomans were heavily engaged with the Austrians in Hungary, and that their fleet rarely sallied forth, the Venetians failed to make use of this opportunity, and, except for the intercept of a supply convoy from Alexandria off Kos in 1662, there was little action.