John III Sobieski
King of Poland

Though Poland-Lithuania was at that time the largest and one of the most populous states of Europe, Sobieski became a king of a country devastated by almost half a century of constant war. The treasury was almost empty and the court had little to offer the powerful magnates, who often allied themselves with foreign courts rather than the state.

Sobieski had a number of long-term plans, including establishing his own dynasty in the Commonwealth, regaining lost territories, and strengthening the country through various reforms. One of his ambitions was to unify Christian Europe in a crusade to drive the Turks out of Europe. At the beginning of his reign, however, the Polish state was in dire fiscal straits and faced military threats to the north. King Louis XIV of France promised to mediate a truce between the Ottomans and Poland so that Sobieski could focus his attentions on Prussia. The negotiations ended in failure and Sobieski's Baltic goals had to be tempered by the immediate reality of the Ottoman threat to the south.

In the autumn of 1674, he recommenced the war against the Ottomans and managed to recapture a number of cities and fortresses including Bratslav, Mogilev, and Bar, which re-established a strongly fortified line defending Poland's southern border in Ukraine. In 1675, Sobieski defeated a Turkish and Tatar offensive aiming at Lviv. In 1676, the Tatars began a counter-offensive and crossed the Dneper, but could not retake the strategic town of Żórawno, and a peace treaty (the Treaty of Żurawno) was signed soon afterwards. Although Kamieniec Podolski and much of Podolia remained a part of the Ottoman Empire, Poland gained the return of the towns of Bila Tserkva and Pavoloch.

The treaty with the Ottomans began a period of peace that was much needed for the repair of the country and strengthening of the royal authority. Sobieski managed to reform the Polish army completely. The army was reorganised into regiments, the infantry finally dropped pikes, replacing them with battle-axes, and the Polish cavalry adopted hussar and dragoon formations. Sobieski also greatly increased the number of cannon and introduced new artillery tactics.

Sobieski wanted to conquer Prussia with Swedish troops and French support. Regaining control of this autonomous province was in the Commonwealth's best interest, and Sobieski also hoped for it to become part of his family domain. To this end he made the secret Treaty of Jaworów (1675), but he achieved nothing. The wars with the Ottoman Empire were not decisively won by the Commonwealth, the ruler of Brandenburg-Prussia made treaties with France, Prussia defeated the Swedish invasion, and Sobieski's plans for the Commonwealth's own military campaign against Prussia was opposed by Commonwealth magnates, many of them taking the Prussian side. Backed by Brandenburg and Austria, internal enemies of Sobieski even planned to dethrone him and elect Charles of Lorraine.

The French-Prussian treaty of 1679 meant that Sobieski lost the major foreign ally for his planned campaign against Prussia; consequently, he started to distance himself from the pro-French faction, which, in turn, resulted in the cooling down of the Polish-French relations. During the Sejm of 1683, the French ambassador was expelled for involvement with a plan to dethrone Sobieski, which definitely marked the end of the Polish-French alliance. At the same time Sobieski made peace with the pro-Habsburg faction and started to gravitate towards an alliance with Austria. This did not end the existence of strong internal opposition to Sobieski; however, it changed a number of allegiances, and further opposition was temporarily weakened through the king's successful political maneuvering, including granting the Grand Hetman office to one of the opposition's chief leaders, Stanisław Jan Jabłonowski.

Conscious that Poland lacked allies and risked war against most of its neighbours (a situation similar to the Deluge), Sobieski allied himself by 1683 with Leopold I, of the Holy Roman Empire. Both sides promised to come to one's another aid if their capitals were threatened. The alliance was signed by royal representatives on 31 March 1683 and ratified by the Emperor and Polish parliament within weeks. Although aimed directly against the Ottomans and indirectly against France, it had the advantage of gaining internal support for the defense of Poland's southern borders. This was a beginning of what would become the Holy League, championed by Pope Innocent XI to preserve Christendom.

Meantime, in the spring of 1683, royal spies uncovered Ottoman preparations for a military campaign. Sobieski feared that the target might be the Polish cities of Lwów and Kraków. To counteract the threat, Sobieski began the fortification of the cities and ordered universal military conscription. In July, the Austrian envoy asked for Polish assistance. Soon afterward, the Polish army started massing for an expedition against the Ottomans, and in August was joined by Bavarians and Saxon allies under Charles of Lorraine.
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