The Campaign
In August 1537 Katzianer's army was encamped near Koprivnica and in September they started marching eastwards towards Virovitica. 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 reached Valpovo where they started making preparations for a strike on Osijek, 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 around Vuka 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 ensuing Battle of Gorjani.
Slavonia is, with Dalmatia, Croatia proper, and Istria, one of the four historical regions of Croatia. Located in the Pannonian Plain and taking up the east of the country, it roughly corresponds with five Croatian counties: Brod-Posavina, Osijek-Baranja, Požega-Slavonia, Virovitica-Podravina, and Vukovar-Syrmia, although the territory of the counties includes Baranya, and the definition of the western extent of Slavonia as a region varies. The counties cover 12,556 square kilometres or 22.2% of Croatia, inhabited by 806,192—18.8% of Croatia's population. The largest city in the region is Osijek, followed by Slavonski Brod and Vinkovci.
John Zápolya or Szapolyai, was King of Hungary from 1526 to 1540. His rule was disputed by Archduke Ferdinand I, who also claimed the title King of Hungary. He was Voivode of Transylvania before his coronation, from 1510 to 1526.
Baron Nikola Jurišić was a Croatian nobleman, soldier, and diplomat.
The Habsburg monarchy and the Ottoman Empire waged a series of wars on the territory of the Kingdom of Hungary and several adjacent lands in Southeastern Europe from 1526 to 1568. The Habsburgs and the Ottomans engaged in a series of military campaigns against one another in Hungary between 1526 and 1568. While overall the Ottomans had the upper hand, the war failed to produce any decisive result. The Ottoman army remained very powerful in the open field but it often lost a significant amount of time besieging the many fortresses of the Hungarian frontier and its communication lines were now dangerously overstretched. At the end of the conflict, Hungary had been split into several different zones of control, between the Ottomans, Habsburgs, and Transylvania, an Ottoman vassal state. The simultaneous war of succession between Habsburg-controlled western "Royal Hungary" and the Zápolya-ruled pro-Ottoman "Eastern Hungarian Kingdom" is known as the Little War in Hungary.
The Kingdom of Croatia was part of the Lands of the Hungarian Crown, but was subject to direct Imperial Austrian rule for significant periods of time, including its final years. Its capital was Zagreb. It was also a part of the lands of the Habsburg monarchy from 1527, following the Election in Cetin, and the Austrian Empire from 1804 to 1867.
The Battle of Szina or Seňa took place near Szina in the Kingdom of Hungary. The battle was fought on 20 March 1528 between two rival kings of Hungary John Zápolya and Ferdinand I. The latter's forces under command of Bálint Török and Johann Katzianer, a Styrian mercenary commander defeated John's army; the battle was the second military defeat for John Zápolya during the civil war.
Johann Katzianer, or Hans Katzianer, Freiherr zu Katzenstein und Fledingen was a Carniolan aristocrat and an Imperial Army commander.
The Battle of Gorjani or Battle of Đakovo was fought on 9 October 1537 at Gorjani, a place in present-day Slavonia, between the towns of Đakovo and Valpovo, as part of the Little War in Hungary as well as the Hundred Years' Croatian–Ottoman War.
The Hundred Years' Croatian–Ottoman War was a sequence of conflicts, mostly of relatively low intensity, between the Ottoman Empire and the medieval Kingdom of Croatia, and the later Habsburg Kingdom of Croatia. Besides periods of small-scale borderland warfare, the conflict also saw episodes of major conquest campaigns of Croatian land undertaken by the Ottomans especially during the 16th century.
The siege of Gvozdansko was an Ottoman siege of the fort of Gvozdansko in the Kingdom of Croatia in 1577–1578. In the 1570s, the Ottomans intensified their efforts to capture the valley of the Una River. A string of forts along the Una, centred around Gvozdansko and in possession of the Zrinski noble family, formed the main line of defense of Croatia since 1527. The fort held off Ottoman attacks in 1540 and 1561.
The siege of Kőszeg or siege of Güns, also known as the German campaign was a siege of Kőszeg in the Kingdom of Hungary within the Habsburg Empire, that took place in 1532. In the siege, the defending forces of the Austrian Habsburg monarchy under the leadership of Croatian Captain Nikola Jurišić, defended the small border fort of Kőszeg with only 700–800 Croatian soldiers, with no cannons and few guns. The defenders prevented the advance of the Ottoman army of over 100,000 toward Vienna, under the leadership of Sultan Suleiman the Magnificent and Pargalı Ibrahim Pasha.
Christoph Frankopan was a Croatian count from the noble House of Frankopan. He was born in a dangerous time, which included the fall of Bosnia to the Ottoman Empire and the start of the Hundred Years' Croatian-Ottoman War. As a supporter of King John I of Hungary during the succession crisis between János Zápolya and Ferdinand Habsburg, he was named the ban of Croatia in 1526, and died the following year while leading an army financed by Zápolya.
Pavle Bakić was the last titular Despot of Serbia. He was one of the most notable military commanders among Serbian nobility in the Kingdom of Hungary, and fought against the Ottoman Empire in several battles, most notably at the Battle of Mohács (1526) and the Battle of Vienna (1529). He fell at the Battle of Gorjani (1537).
Radič Božić was titular Despot of Serbia, from 1527 until his death in September 1528. He was one of the most notable military commanders among Serbian nobility in the Eastern Hungarian Kingdom, and fought against the Ottoman Empire in several battles, most notably the Battle of Mohács.
The Bakić family was a Serbian noble family that initially held estates in Šumadija under Ottoman occupation, then crossed the river and gave its service to the Kingdom of Hungary, becoming one of the leading Serbian noble family in the country, fighting the Ottoman Empire.
The siege of Virovitica was one of the first battles of the Croatian–Slavonian theater during the Great Turkish War. The siege took place in July 1684, and it ended with the Ottoman garrison's surrender and Habsburg-Croatian capture of Virovitica. Due to its capture in the early phase of the war, the town became a vital Habsburg base for further operations in Slavonia.
The Great Turkish War of 1684–1689 saw conflict between the Holy League and the Ottoman Empire in territories of Croatia, Slavonia and Dalmatia. The war was concluded by the Treaty of Karlowitz in 1699, which significantly eased the Ottoman grip on Croatia.
Osijek Campaign of 1685 was a successful Habsburg-Croatian raid towards the town of Osijek in Ottoman held Slavonia. Although the campaign inside enemy territory ended in a tactical victory for Habsburg-Croatian troops, James Leslie - the general in charge, decided for a tactical withdrawal after reaching Osijek and defeating one Ottoman army there, because he lacked sufficient heavy weapons to besiege Osijek's main fort.
The Siege of Valpovo took place at Valpovo, now part of Croatia, from May to June 1543. It was part of the Ottoman-Habsburg War (1540–1547), as well as the Hundred Years' Croatian–Ottoman War. The siege resulted in an Ottoman victory.
The Ottoman-Habsburg War (1529–1533), the first of a long series of wars between the Habsburg and Ottoman Empire.
Ottoman Empire 
Johann Katzianer 
Albrecht Schlick 
Petar Keglević 
Pavle Bakić † 
