The siege of Klis or Battle of Klis (, ) was a siege of Klis Fortress in the Kingdom of Croatia within Habsburg monarchy. The siege of the fortress, which lasted for more than two decades, and the final battle near Klis in 1537, were fought as a part of the Ottoman–Habsburg wars between the defending Croatian–Habsburg forces under the leadership of Croatian feudal lord Petar Kružić, and the attacking Ottoman army under the leadership of the Ottoman general Murat-beg Tardić.
After the decisive Ottoman victory at the Battle of Krbava Field in 1493, and especially after the Battle of Mohács in 1526, the Croats continued defending themselves against the Ottoman attacks. The Ottoman conquest during the early years of the 16th century prompted the formation of the Uskoks, which were led by Croatian captain Petar Kružić, also called Prince of Klis. As a part of the Habsburg defensive system, Uskoks used the base at Klis as an important defensive position. They fought almost alone against the Ottomans, and for more than two decades defended the fortress against the Ottoman attacks.
After the final battle, which resulted in an Ottoman victory and in Petar Kružić's death, the Klis defenders, who were lacking in water supplies, finally surrendered to the Ottomans in exchange for their freedom on 12 March 1537. Citizens fled the town, while the Uskoci retreated to the city of Senj, where they continued fighting the Ottoman army. Klis became an administrative centre or sanjak (Sanjak of Klis) of the Bosnia Eyalet, and would remain so for a century.
Background
After the fall of the Kingdom of Bosnia into Ottoman hands in 1463, the southern and central parts of the Kingdom of Croatia remained unprotected, the defense of which was left to Croatian gentry who kept smaller troops in the fortified border areas at their own expense. The decisive Ottoman victory at the Battle of Krbava Field in 1493 shook all of Croatia. However, it did not dissuade the Croats from making more decisive and persistent attempts at defending themselves against the attacks of the much larger enemy. A new wave of Ottoman conquest began in 1521, after which a good portion of Croatia was conquered or pillaged.
On 29 August 1526, at the Battle of Mohács, the Christian forces led by King Louis II were defeated by Ottoman forces led by Sultan Suleiman the Magnificent. Louis was killed in the battle, which resulted in the end of the independent Kingdom of Hungary as he died without an heir. Both the Kingdoms of Hungary and Croatia became disputed territories with claims from both the Habsburg and Ottoman empires. Ferdinand I, Archduke of Austria, a member of the House of Habsburg, the brother of Holy Roman Emperor Charles V and a future Holy Roman Emperor himself, married the sister of Louis II and was elected King by the nobles of both Hungary and Croatia.
Owing to its location, Klis Fortress was an important defensive position during the Ottoman conquest of the Balkans. The fortress stands along the route by which the Ottomans could penetrate the mountain barrier separating the coastal lowlands from around Split, from Ottoman-held Bosnia. The Croat feudal lord Petar Kružić gathered together a garrison composed of Croat refugees, who used the base at Klis both to hold the Ottomans at bay, and to engage in marauding and piracy against coastal shipping. Although nominally accepting the sovereignty of the Habsburg Emperor Ferdinand, who obtained the Croatian crown in 1527, Kružić and his freebooting Uskoks were a law unto themselves.
Siege
Failed attempts
From 1513, Petar Kružić was one of the commanding officers of Klis Fortress. The Ottomans attempted to conquer the Klis Fortress on several occasions. The first major attempt was by Skender-beg Ornosović in 1515. The Ottomans captured Klis, a village just below the fortress bearing the same name, but the garrison in the fortress above held. Kružić was promoted to captain of the Klis Fortress by the ban Petar Berislavić in 1520. The second major attempt was in 1520, and a year later another attempt was made by Makut-paša, with additional 2,000 infantry, 50 horsemen, and siege equipment. Another unsuccessful attempt was made in 1522, by Hasan-paša from Mostar and Mehmed-beg Mihalbegović. Later that year, Mihalbegović made another attempt at a siege with 3,000 men, but failed again. During 1523, Klis Fortress was again under attack by the Sultan's army. Attempts were also made by Gazi Husrev-beg in 1526 and 1528, and later in 1531 and 1532.