structural:summarization
1683–1699: Great Turkish War – Loss of Hungary and the Morea

The Great Turkish War started in 1683, with a grand invasion force of 140,000 men marching on Vienna, supported by Protestant Hungarian noblemen rebelling against Habsburg rule. To stop the invasion, another Holy League was formed, composed of Austria and Poland (notably in the Battle of Vienna), Venetians and the Russian Empire, Vienna had been besieged by the Ottoman Empire for two months. The battle marked the first time the Polish–Lithuanian Commonwealth and the Holy Roman Empire had cooperated militarily against the Ottomans, and it is often seen as a turning point in history, after which "the Ottoman Turks ceased to be a menace to the Christian world". In the ensuing war that lasted until 1699, the Ottomans lost almost all of Hungary to the Holy Roman Emperor Leopold I.

After winning the Battle of Vienna, the Holy League gained the upper hand and reconquered Hungary (Buda and Pest were retaken in 1686, the former under the command of a Swiss-born convert to Islam). At the same time, the Venetians launched an expedition into Greece, which conquered the Peloponnese. During the 1687 Venetian attack on the city of Athens (conquered by the Ottomans), the Ottomans turned the ancient Parthenon into an ammunitions storehouse. A Venetian mortar hit the Parthenon, detonating the Ottoman gunpowder stored inside, partially destroying it.

The war ended with the Treaty of Karlowitz in 1699. Prince Eugene of Savoy first distinguished himself in 1683 and remained the most important Austrian commander until 1718.