| Conflict: | Siege of Jajce |
| Date: | 10 July – 22 August 1464 |
| Place: | Jajce Fortress Hungarian banate of Jajce (modern-day Bosnia and Herzegovina) |
| Result: | Hungarian victory |
| Combatant1: | Ottoman Empire |
| Commander1: | Mehmed II Mehmed Bey |
| Commander2: | Emeric Zápolya |
| Units2: | Garrison |
| Strength1: | 30,000 men |
The siege of Jajce took place between 10 July and 22 August 1464, during the Ottoman conquest of Bosnia and Herzegovina, when an Ottoman army under Sultan Mehmed II made a new attempt to conquer Bosnia and take control of the strategic fortress of Jajce, south of Banja Luka, at the time under Hungarian control.
Despite massive bombardment, the final Ottoman assault was heavily repulsed and after hearing that King Mathias of Hungary was approaching with a relief army, Mehmed abandoned the siege.
In 1463 Mehmed II invaded and occupied Bosnia, at the time under Hungarian suzerainty, executing its catholic King Stephen Tomašević, despite promising him safety if he surrendered.
In September 1463, under the aegis of Pope Pius II and the (Habsburg) Holy Roman Empire, Hungary and Venice (as well as Philip the Good's Duchy of Burgundy) forged an alliance to resist Ottoman Turkish conquests in Serbia. In December 1463 the strategic fortress of Jajce, south of Banja Luka, was retaken by King Matthias Corvinus of Hungary, John Hunyadi's son, after a siege that followed a counterattack into Bosnia in late September 1463.
After the reconquest of Jajce, numerous other Bosnian fortified towns opened their doors to the Hungarian troops. The part of Bosnia reconquered from the Ottomans was organized into a banate with Jajce as its capital and Emeric Zápolya as its governor.
In July 1464, Ottoman Sultan Mehmed II, determined to take back Jajce, ordered a fresh offensive into Bosnia. Mehmed personally commanded a force including 30,000 men and a large siege train, including six stone throwing cannons.
The Ottoman army had probably set out from Edirne in late May according to C. Imber, 'since Malipiero dates the siege of Jajce to between 10 July and 24 August, and Enveri [...] also says that it began in July'.
The main body of the Ottoman army reached Jajce on 10 July 1464. In spite of more than six weeks of massive mining and bombardment, the Hungarian defence held up managing to repulsed Turkish attacks. On 22 August Mehmed ordered an assault for the next morning on three sides, following heavy casualties the Ottomans were again driven back. As news of King Corvinus' advance with a relief force from the Sava reached the Ottoman army, Mehmed II decided to abandon the baggage train, throw his cannons into the river, and retreat to Sofia on 22 August where the army wintered.[1]
Mehmed Bey Minnetoğlu was appointed the governor of Bosnia after this second siege of Jajce.
Although Hungarian forces successfully maintained control over Jajce and portions of northern Bosnia, the remaining territory succumbed to the Ottomans, who achieved complete dominance by 1483 after the fall of Herzegovina.