The Siege ofBelgrade in 1521 is an event that followed as a result of the third major Ottoman attack on this Hungarian stronghold in the Ottoman–Hungarian wars at the time of the greatest expansion of the Ottoman Empire to the west. Ottoman SultanSuleiman the Magnificent decided that the first targets of his military campaigns would be Rhodes and Belgrade, a place that his ancestor Mehmed the Conqueror failed to conquer. Suleiman launched his army in mid-May 1521, and the main objective of this march was to conquer Belgrade. The Hungarian state was almost in disarray and unable to effectively counter the Ottoman army. Unlike previous campaigns, the Sultan decided this time that the main direction of attack was to go from the Sava. To do this, the Ottoman army first had to capture Srem, which was eventually done. Belgrade defenders persisted in resisting, but due to lack of manpower and war material, they had to surrender the city on 28/29 August 1521. The fall of Belgrade showed the inability of the Hungarian authorities to oppose the expansionist policies of the Ottoman Empire, which would show their supremacy in the Battle of Mohács plains in 1526. After the defeat and breakdown of Hungary, the leader of the Christian struggle against the Ottoman penetration of Europe would become the Habsburg Monarchy, which would include Hungary. Belgrade would come under the rule of a Christian force only in 1688 when Maximilian Bavarian conquered it for Austria. When Selim I died, his son Suleiman became sultan of the Ottoman Empire in 1520, on the other hand the Kingdom of Hungary was almost in ruins. The Hungarian nobility was divided into numerous parties, and without a strong central government it could not unite in defense of the country. King Louis II of Hungary was weakened by numerous conflicts. The lower nobility clashed with the higher nobility and court circles, and the Duke of Erdelj, John Zapotya, one of the wealthiest greats of his time, represented open opposition to the already weak regime of King Louis II. The faction that supported the Duke of Erdel was in constant conflict with the court circles. The king himself was a powerless figure in the hands of his ambitious associates. He often did not have the money for his own existence. On such occasions, it was not possible to strengthen the defense system at the southern border and to undertake any military campaigns.
