The Ottoman Advance on Vienna

The Ottoman Empire in 1683 was not a declining power — it was the strongest military state in Europe, with a professional army, a professional bureaucracy, and a tax base that dwarfed any single European kingdom. The Köprülü grand viziers had restored its fighting strength after the mid-century crises, and Kara Mustafa Pasha, the last and most ambitious of the line, believed the moment had come to finish what Suleiman the Magnificent had started in 1529: the conquest of Vienna and, with it, the heart of Christian Europe.

The road was open. Imre Thököly, a Hungarian Protestant nobleman in revolt against Habsburg rule, had allied with the Ottomans and controlled much of Upper Hungary. Louis XIV of France, the other great enemy of the Habsburgs, was pressing them on the Rhine. Leopold I was distracted, underfunded, and militarily overextended. When the Ottoman army mustered at Edirne in the spring of 1683, it was the largest force the empire had fielded in decades — estimates range from 100,000 to 200,000 men, with thousands of auxiliary troops, a massive siege train, and a vast supply column.

Leopold fled Vienna on July 7, taking the court and much of the population with him to Passau. He left Ernst Rüdiger von Starhemberg in command of a garrison of roughly 15,000 men with orders to hold the city at all costs. The fortifications were old-fashioned by western standards — Vienna had not been modernized with the Italian-style bastions that made other cities nearly impregnable — and Kara Mustafa's engineers were experienced siege operators. Everything depended on whether help would arrive in time.

From Passau, Leopold sent desperate appeals to every Christian prince who might listen. The most important reply came from Jan III Sobieski, King of Poland, who had his own score to settle with the Ottomans. Pope Innocent XI brokered the alliance and helped finance it. The race between the miners under the walls and the army marching over the mountains had begun.