After the Battle of Mohács, where King Louis II of Hungary was killed, John Zápolya, Voivode of Transylvania, ascended to the Hungarian throne.
However, Archduke Ferdinand of Austria also claimed the throne through the House of Habsburg intermarriages with Louis II's Jagiellon dynasty.
Zápolya recruited a new army, and in 1528 advanced into Hungary with approximately 15,000 men, including Transylvanian, Polish, and Serbian troops, but few Hungarians.
Carniolan Johann Katzianer and Bálint Török marched against Zápolya with an army recruited from Hungary, Austria, and the German states of the Holy Roman Empire, numbering approximately 13,000–14,000 men.
Petru Rareş defeated Ferdinand in the Battle of Földvár (Hungarian: Földvári csata, German: Schlacht bei Marienburg, Romanian: Bătălia de la Feldioara), and the Ottoman army (including Moldavians and Serbs) lay Siege of Vienna.