The years from 1529 to 1552 were known as the "Little War".
Following Suleiman's unsuccessful siege of Vienna in 1529, Ferdinand launched a counter-attack in 1530 to regain the initiative.
An assault on Buda was driven off by John Zápolya, although Ferdinand was successful elsewhere—capturing Gran (Esztergom) and other forts along the Danube river, a vital strategic frontier.

Suleiman's response came in 1532 when he led a massive army of over 120,000 troops to besiege Vienna again.
Ferdinand withdrew his army, leaving only 700 men with no cannons and a few guns to defend Güns (Koszeg) although Ibrahim Pasha, the Grand Vizier of the Ottomans, did not realize how poorly defended Koszeg was.
Suleiman came to join him shortly after the Siege of Güns had started.
For more than 25 days, Croatian captain Nikola Jurišić and his garrison of 800 Croats held out against 19 full-scale assaults and an incessant bombardment by the over 120,000 Ottomans.
As a result, the city was offered a surrender on favourable terms and, although the offer was rejected, the Ottomans retreated leading to a peace treaty between Ferdinand and Suleiman.
John Zápolya was recognized as the King of Hungary by the Habsburgs, although as an Ottoman vassal.

The treaty did not satisfy either John Zápolya or Ferdinand, and their armies began skirmishes along the borders.
In 1537, Ferdinand attacked John's forces at Osijek in violation of the treaty.
The siege was a disaster of similar magnitude to that of Mohács, with an Ottoman relief army smashing the Austrians.
Rather than attack Vienna again, Suleiman attacked Otranto in southern Italy.
At the naval Battle of Preveza in 1538, the Ottomans inflicted another defeat on the Habsburg-led coalition.

John Zápolya died in 1540 and was succeeded by his infant son John II Sigismund Zápolya.
For much of his reign, the country was governed by his mother Isabella Jagiellon, with continued support from Suleiman.
John II remained the nominal King of Hungary until he abdicated in 1570 and returned the country to Habsburg rule.

A further humiliating defeat was inflicted on the Habsburgs in the 1541 Siege of Buda, when the Ottomans responded to a request for help from Isabella Jagiellon.
In April 1543, Suleiman launched another campaign in Hungary, taking back Bran and other forts and returning much of Hungary to Ottoman control.
In August 1543, the Ottomans succeeded in the Siege of Esztergom, which was followed by the capture of three Hungarian cities: Székesfehérvár, Siklós, and Szeged, offering better security for Buda.

Another peace agreement between the Habsburgs and the Ottomans lasted until 1552, when Suleiman decided to attack Eger.
The siege proved futile, and the Habsburg victory reversed a period of territorial losses in Hungary.
Their retention of Eger gave the Austrians good reason to believe that Hungary was still contested ground and the Ottoman campaign in Hungary ended, until its revival in 1566.
The years from 1529 to 1552 were known as the "Little War". Following Suleiman's unsuccessful siege of Vienna in 1529, Ferdinand launched a counter-attack in 1530 to regain the initiative. An assault on Buda was driven off by John Zápolya, although Ferdinand was successful elsewhere—capturing Gran (Esztergom) and other forts along the Danube river, a vital strategic frontier.
Suleiman's response came in 1532 when he led a massive army of over 120,000 troops to besiege Vienna again. Ferdinand withdrew his army, leaving only 700 men with no cannons and a few guns to defend Güns (Koszeg) although Ibrahim Pasha, the Grand Vizier of the Ottomans, did not realize how poorly defended Koszeg was. Suleiman came to join him shortly after the Siege of Güns had started. For more than 25 days, Croatian captain Nikola Jurišić and his garrison of 800 Croats held out against 19 full-scale assaults and an incessant bombardment by the over 120,000 Ottomans. As a result, the city was offered a surrender on favourable terms and, although the offer was rejected, the Ottomans retreated leading to a peace treaty between Ferdinand and Suleiman. John Zápolya was recognized as the King of Hungary by the Habsburgs, although as an Ottoman vassal.
The treaty did not satisfy either John Zápolya or Ferdinand, and their armies began skirmishes along the borders. In 1537, Ferdinand attacked John's forces at Osijek in violation of the treaty. The siege was a disaster of similar magnitude to that of Mohács, with an Ottoman relief army smashing the Austrians. Rather than attack Vienna again, Suleiman attacked Otranto in southern Italy. At the naval Battle of Preveza in 1538, the Ottomans inflicted another defeat on the Habsburg-led coalition.
John Zápolya died in 1540 and was succeeded by his infant son John II Sigismund Zápolya. For much of his reign, the country was governed by his mother Isabella Jagiellon, with continued support from Suleiman. John II remained the nominal King of Hungary until he abdicated in 1570 and returned the country to Habsburg rule.
A further humiliating defeat was inflicted on the Habsburgs in the 1541 Siege of Buda, when the Ottomans responded to a request for help from Isabella Jagiellon. In April 1543, Suleiman launched another campaign in Hungary, taking back Bran and other forts and returning much of Hungary to Ottoman control. In August 1543, the Ottomans succeeded in the Siege of Esztergom, which was followed by the capture of three Hungarian cities: Székesfehérvár, Siklós, and Szeged, offering better security for Buda.
Another peace agreement between the Habsburgs and the Ottomans lasted until 1552, when Suleiman decided to attack Eger. The siege proved futile, and the Habsburg victory reversed a period of territorial losses in Hungary. Their retention of Eger gave the Austrians good reason to believe that Hungary was still contested ground and the Ottoman campaign in Hungary ended, until its revival in 1566.
Siege of Szigetvár