We came, we saw, God conquered.— Jan Sobieski, announcing the relief of the siege of Vienna from the Ottoman Turks in 1683
When the Thirty Years War and Peace of Westphalia stifled Austrian ambitions in Germany, the Hapsburgs expanded eastward against the Ottoman Empire. Ever since the death of Suleiman the Magnificent in 1565, the Ottoman Empire had been in serious decline, with a corrupt government, rebellious army, obsolete military technology, and decaying economy. Such a faltering empire was a tempting target for its neighbors. However, the Hapsburgs were never able to concentrate solely on the Turks. This was because France under Louis XIV posed a constant threat of invasion to the various German states, which forced the Hapsburgs to divide their attention between east and west.
The Hapsburg ruler at this time was Leopold I (1657-1705), a mediocre ruler, but lucky enough to have capable generals to lead his armies. Leopold's main goal was control of Hungary, which had been divided between Turkish and Austrian rule for over a century. When Leopold supported rebels in Transylvania against the Turks, war and an Ottoman invasion resulted. At this time, the Turks were ruled by an able family of viziers, the Koprulus, who started reforming the state in order to make the Ottomans a power to contend with once again. As a result, when the Turkish army started to advance westward, the alarm went up all over Europe, with even Louis XIV sending 4000 troops to help the Hapsburgs (and make himself look like a good Christian). In 1664, a much smaller, but better equipped and trained allied army caught and destroyed a Turkish army while it was crossing the Raba River. This was the first major victory of a Christian army over the Ottomans. However, it encouraged Leopold's allies to feel secure enough to take their troops home, leaving him to face the Turks alone. Instead of continuing the fight, he signed a humiliating peace that damaged his reputation considerably. As a result, the Hungarian nobles under his rule rebelled and called in the Turks to help them.
This triggered the Turks' last major invasion of Europe, climaxing at the siege of Vienna in 1683. A huge Turkish army of possibly 150,000 men, but with no large siege artillery, was faced by only the stout walls of Vienna and a garrison of ll,000 men. The siege lasted two months as the Turks gradually used the old medieval technique of undermining the walls. Just as the hour of their victory approached, a relief army from various European states arrived and crushed the Turkish army. From 1683 to 1700, Hapsburg forces and their allies advanced steadily against the Turks, only being interrupted by having to meet French aggression in the West. In 1697, the allied forces demolished another Turkish army at Zenta and watched as the once proud Janissaries murdered their own officers in the rout. The resulting treaty of Karlowitz (1699) gave Austria all of Hungary, Transylvania, and Slavonia. Karlowitz re-established Austria, now also known as Austria-Hungary, as a major European power. From 1700 until the end of World War I in 19l8, the Hapsburg Empire would dominate southeastern Europe, while the Ottoman Empire staggered on as the "Sick Man of Europe."
Although the Hapsburg Empire had regained its status as a military and diplomatic power, it still had serious internal problems, namely a powerful nobility ruling over enserfed peasants, a hodge-podge of peoples with nothing in common except that they all called Leopold their emperor, and a variety of states that each had their own rights, privileges and governmental institutions. The Hapsburgs dealt with these problems in three ways. First of all, they neutralized the nobles politically by making a deal that let them continue to oppress the peasants as long as they did not interfere in the government. This left the nobles fairly happy while giving the Hapsburgs a free hand to run the state, largely with soldiers and bureaucrats recruited from other parts of Europe. Unfortunately, this also left the empire socially and economically backward. Second, they tried to unite their empire religiously and culturally by imposing the Catholic faith and promoting the German language throughout their empire. Trying to submerge native cultures, such as that of Bohemia, under Catholicism and German culture mostly caused resentment against Hapsburg rule. Finally, they ruled each principality (Austria, Hungary, Bohemia, etc.) separately with its own customs and institutions. This kept nobles of different provinces from being able to combine in revolts against the Hapsburgs, but it also left the empire fragmented into a number of separate provinces. A large standing army and bureaucracy also held the empire together.
For the next two centuries the Hapsburg Empire would be a major power in Europe. However, it had a number of serious problems that it never adequately solved, being socially and economically backward and fragmented into a large number of provinces and increasingly restless ethnic groups. Together, these problems gradually ate away like a cancer at the Hapsburg Empire, rotting it out from within until there was hardly anything left to hold it together by the twentieth century.