Hungarian campaign of 1527–1528

The Hungarian Civil War (Hungarian: Magyar Belháború) or campaign of 1527–1528 was launched by Ferdinand I, Archduke of Austria and King of Hungary and Bohemia and his Hungarian followers against the Ottoman Turks. Following the Battle of Mohács, the Ottomans were forced to withdraw as events elsewhere in their now massive Empire required the Sultan's attention. Seizing upon their absence, Ferdinand I attempted to enforce his claim as King of Hungary. In 1527 he drove back the Ottoman vassal John Zápolya and captured Buda, Győr, Komárom, Esztergom, and Székesfehérvár by 1528. Meanwhile, the Ottoman Sultan, Suleiman the Magnificent, took no action at this stage despite the pleas of his vassal.

The civil war was preceded by Louis II of Hungary died and the Turks besieged Buda. During this era Hungary broke into 3.: Royal Hungary, Kingdom of Eastern Hungary (or Kingdom of Zápolya) and Ottoman Hungary (and some self-governing regions). Zápolya's followers invoked the decision of the Diet of the Estates, while Ferdinand's followers invoked the blood relationship between the Árpád dynasty and the House of Habsburg (from the First Congress of Vienna).

Aftermath
on 10 May 1529, Suleiman the Magnificent launched his own counter-attack negating all of Ferdinand's gains. Many of the recently captured forts surrendered without resistance, greatly speeding up the advance. As a result, Suleiman was able to reach and besiege Vienna.