Ahmed II ( Aḥmed-i sānī) (25 February 1643 or 1 August 1642 – 6 February 1695) was the Sultan of the Ottoman Empire from 1691 to 1695. Early life Ahmed II was born on 25 February 1643 or 1 August 1642, the son of Sultan Ibrahim and Muazzez Sultan. On 21 October 1649, Ahmed, along with his brothers Mehmed and Suleiman were circumcised. During the reigns of his older brothers, Ahmed was imprisoned in Kafes, and he stayed there almost 43 years. Reign During his reign, Ahmed II devoted most of his attention to the wars against the Habsburgs and related foreign policy, governmental and economic issues. Of these, the most important were the tax reforms and the introduction of the lifelong tax farm system (malikâne). Following the recovery of Belgrade under his predecessor, Suleiman II, the military frontier reached a rough stalemate on the Danube, with the Habsburgs no longer able to advance south of it, and the Ottomans attempting, ultimately unsuccessfully, to regain the initiative north of it. Among the most important features of Ahmed's reign was his reliance on Köprülüzade Fazıl Mustafa Pasha. Following his accession to the throne, Ahmed II confirmed Fazıl Mustafa Pasha in his office as grand vizier. In office from 1689, Fazıl Mustafa Pasha was from the Köprülü family of grand viziers, and like most of his Köprülü predecessors in the same office, was an able administrator and military commander. Like his father Köprülü Mehmed Pasha (grand vizier, 1656–61) before him, Fazıl Mustafa Pasha ordered the removal and execution of dozens of corrupt state officials of the previous regime and replaced them with men loyal to himself. He overhauled the tax system by adjusting it to the capabilities of the taxpayers affected by the latest wars. He also reformed troop mobilization and increased the pool of conscripts available for the army by drafting tribesmen in the Balkans and Anatolia. In October 1690, Fazıl Mustafa Pasha recaptured Belgrade, a key fortress that commanded the confluence of the rivers Danube and Sava; in Ottoman hands since 1521, the fortress had been conquered by the Habsburgs in 1688. Fazıl Mustafa Pasha's victory at Belgrade was a major military achievement that gave the Ottomans hope that the military debacles of the 1680s—which had led to the loss of Hungary and Transylvania, an Ottoman vassal principality ruled by pro-Istanbul Hungarian princes—could be reversed. However, the Ottoman success proved