After the Thirty Years’ War, Austrian rulers were understandably reluctant to enter into another military conflict. In 1654 Ferdinand IV, the eldest son of the emperor, died. His brother, the future emperor Leopold I, who had been destined for a church career, was then considered as heir to the throne and was recognized as such by Austria, Bohemia, and Hungary. In Germany, however, difficulties arose when France declared itself against Leopold. Nevertheless, following the death of Emperor Ferdinand, Leopold was finally elected (1658) after having conceded constitutional limitations that restricted his liberty of action in foreign politics. West German princes under Johann Philipp von Schönborn, archbishop of Mainz, formed the French-oriented League of the Rhine. At the same time, Austria was engaged in the northeast when it intervened in the war between Sweden and Poland (1658) in order to prevent the collapse of Poland. There were some military successes, but the Treaty of Oliva (1660) brought no territorial gains for Austria, though it stopped the advance of the Swedes in Germany.

During the Thirty Years’ War the Turkish front had been quiet, but in the 1660s a new war broke out with the Turks (1663–64) because of a conflict over Transylvania, where a successor had to be appointed for György II Rákóczi, who had been killed fighting against the Turks. The Turks conquered the fortress of Neuhäusel in Slovakia, but the imperial troops succeeded in throwing them back. The Austrian military success was not, however, reflected in the terms of the Treaty of Vasvár: Transylvania was given to Mihály Apafi, a ruler of pro-Turkish sympathies. A minor territorial concession was also made to the Turks. The year after the Turkish peace, Tirol and the Vorlande reverted to Leopold I (1665), and the second period of the Habsburg partition (1564–1665) came to an end.

In Hungary dissatisfaction with the results of the Turkish war spread. Not only the Protestants, who were threatened by the Counter-Reformation, but also many Catholic nobles were alarmed by Habsburg absolutism. A group of Hungarian nobles and Steiermark’s Count Hans Erasmus of Tattenbach entered into a conspiracy. The Austrian government, informed of their activities, had four of the ringleaders executed—an action that led to a rising by rebels known as Kuruzen (Crusaders).

In the meantime, the position of the Habsburgs in the west had again deteriorated. At first, Leopold I’s leading statesmen, Johann Weikhart, Fürst (prince) von Auersperg (dismissed in 1669), and the president of the Court Council of War, Wenzel Eusebius, Fürst von Lobkowitz, remained rather passive in view of the expansionist policies of Louis XIV of France. They also stayed outside the Triple Alliance of Holland, England, and Sweden that was concluded in order to ward off the attacks of Louis against the Spanish Netherlands. When Louis actually invaded Holland, the emperor finally entered the war, but, in the ensuing Treaties of Nijmegen (1679), he had to cede Freiburg im Breisgau to France.

Another and still more menacing danger appeared in the southeast. After some deliberation the leader of the Hungarian rebels, Imre Thököli, had asked the Turks for help, whereupon the grand vizier Kara Mustafa Pasa organized a large Turkish army and marched it toward Vienna. Habsburg diplomats succeeded in concluding an alliance between Austria and Poland. Meanwhile, imperial troops under Charles IV (or V) Leopold, duke of Lorraine and Bar, tried to hold back the Turks but had to retreat. From July 17 to September 12, 1683, Vienna was besieged by the Turks. Deciding against a direct assault, the Turks had begun to drill tunnels underneath the bastions of the city when relief columns arrived from Bavaria, Saxony, Franconia, and Poland. King John III Sobieski of Poland took over the command of the relieving army, which descended upon the Turks and dispersed them. The emperor concluded a pact with Poland and the Venetian republic known as the Holy League. In 1685 Neuhäusel was won back, and in September 1686 Ofen (Buda) was captured despite fierce Turkish resistance.

In 1687 the Hungarian diet recognized the hereditary rights of the male line of the Habsburgs to the Hungarian throne. In 1688 Belgrade, Serbia, was conquered, and Transylvania was secured by imperial troops. Meanwhile, Louis XIV had begun an offensive against the German Palatinate that grew into the War of the Grand Alliance. This war meant that no further troops could be spared for the Turkish war, and in 1690 all recent conquests in the south, including Belgrade, were lost again. A victory of the imperial and the allied German troops under Margrave Louis William I of Baden-Baden near Slankamen, Serbia, (1691) prevented the Turks from advancing farther, but then the margrave was ordered to the Rhine front. Eventually Prince Eugene of Savoy took over the command and gained a decisive victory over the Turks in the Battle of Zenta (1697). After another offensive against Bosnia, the Turks finally decided to negotiate a peace. In the Treaty of Carlowitz (1699) Hungary, Transylvania, and large parts of Slavonia (now in Croatia) fell to the Habsburg emperor. Meanwhile, the war in the west, overshadowed already by the question of the Spanish succession, had come to an end with the Treaty of Rijswijk (1697).