Katzianer's Campaign
Part of theHundred Years' Croatian–Ottoman War
A map of 1537 Katzianer's Campaign.
Date August–October 1537 Location Slavonia Result Ottoman victory
Belligerents
Habsburg Monarchy Kingdom of Hungary Kingdom of Croatia Archduchy of Austria Duchy of Carniola Duchy of Styria County of Tyrol	Ottoman Empire
Commanders and leaders
Johann Katzianer  Albrecht Schlick Petar Keglević Pavle Bakić †	Mehmed-beg Jahjapašić
Strength
24,000 16,000 infantry 8,000 cavalry 7–8 large cannons 40 field cannons	8,000
Casualties and losses
20,000 at Gorjani. Several hundred during siege.	Negligible

Katzianer's Campaign orKatzianer's War (Croatian: Katzianerova vojna) was a failed 1537 Habsburg attempt of driving the Ottomans away from the region ofSlavonia in modern-dayCroatia. Despite being well-resourced, Katzianer's army failed to achieve any objectives, and it was ultimately completely annihilated in theBattle of Gorjani.

After Hungarian defeat in theBattle of Mohacs, Croatian nobility electedFerdinand I Habsburg as their new king in theDiet of Cetingrad, while Hungarian and Slavonian nobility electedJohn Zapolya, which plummeted the kingdom into acivil war between two rival kings. By 1528 Ferdinand managed to gain the upper hand over Zapolya in Hungary, however, Zapolya in turn swore an oath to the Ottoman sultan and became his vassal. By spring of 1537, Ferdinand decided to take more decisive effort against the Ottomans so he sent his seasoned commander Johann Katzianer toKriževci to assemble an army and make preparations for the conquest ofOsijek, which was supposed to cut the way for the Ottoman forces betweenBelgrade and Hungary and prevent their further advance to western Slavonia.

In August 1537 Katzianer's army was encamped nearKoprivnica and in September they started marching eastwards towardsVirovitica. Disagreements soon inflamed between Katzianer and Schlick over the command of the troops as well as between Czech and Styrian soldiers in the army. By September 10 Katzianer's forces reached Virovitica where they ran out of food and became further eroded by maladies due to the autumn rains.

By mid-September, the army reachedValpovo where they started making preparations for a strike onOsijek, however, Ottomans sent a 5,000 strong reinforcement to the town which mitigated Katzianer's chances for a regular siege. After achieving nothing near Osijek, the army attempted to withdraw back to Valpovo, however Ottomans had cut off their way so instead they decided to maneuver southwest into swampy areas aroundVuka river, while also being constantly harassed by the Ottoman attacks. By October 7, the hungry and exhausted army reached Gorjani, hoping to march north towards Valpovo in search for food, however remaining troops found out that Katzianer and some other leading commanders had already deserted them. The remnants of this army were crushed by the Ottomans in the ensuingBattle of Gorjani.

Disaster of this campaign enraged Emperor Ferdinand so Katzianer was tried for cowardice and thrown in prison. He subsequently escaped prison and killed a peasant along the way, only to be captured and executed in 1539 on orders ofNikola IV Zrinski.

• Kacijaner, Ivan,Croatian Encyclopedia
• Klaić, Vjekoslav,History of the Croats (Povijest Hrvata), Matica hrvatska, 1988.
• Tracy, James D. (2016).Balkan Wars: Habsburg Croatia, Ottoman Bosnia, and Venetian Dalmatia, 1499–1617. Rowman & Littlefield Publishers.ISBN 978-1-4422-1360-9.

• Battles involving Habsburg Croatia
• 16th-century military history of Croatia
• Military campaigns involving Croatia
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