*Enemies of Poland at this time: Sweden, Brandenburg (Prussia), Russia, Tatars,
Turks and Cossaks.
*Early in his military career he fought against Cossaks (Ruthenian-Poles), Turks, and
Tatars (Originally Mongol hoardesmen, then living south-east of Poland).
*Aided Sweden against Prussia in 1654-55 while being pressured by Russia, only later to expel the Swedes from the captured Prussian territories.
*Became Polish Hetman 1668.
*In 1672. the Turks invaded the Polish Commonwealth and imposed the treaty of Buczacz on the
Poles by which Turkey occupied Podolia and the southern part of the Kiev region.
*In 1673, Sobieski defeated the Turks at Chocim, ensuring  Sobieski's election to the throne.
*1673 battle at Hotin, Bessarabia, defeating the Turks.
*Elected King of Poland 1673 (Wettin dynasty).
*Empire included at this time Poland, Lithuania (Other Baltic territories) , Slovakia, parts of the Ukraine and Bialyrussia.

*Turks (Ottomans) allied with Tatars and Swedes.
*2 historical routes into Europe from the south:
The Danube valley into Vienna,  or the Moldavian plain into southern Poland.
*An agreement was made between Austria and Poland for mutual defense of Vienna/Krakow if either were attacked from the south by the Turks or their allies.
*At he request of the Pope, Sobieski joined his Polish-Lithuanian army of 20,000-30,000 men in an allied force under Charles V Lorraine (Austrians, Germans and Lorrainians of 50,000 men).
These 70,000-80.000 were pitted against 275,000-300,000 Turks and Tatars and Swedes.

*July 14, 1683 Turks arrive at Vienna.
*September 1, 1683 Turks breach defenses at Vienna by exploding a mine under a defense wall.
*Jan Sobieski had a victory at Kahlenberg on September 1, 1683 seriously weakening the Turks,
enabling the saving of Vienna.  It was then that an intensive counter-offensive began, leading to the liberation of Hungary and other parts of the future Austrian empire.
*12 September, 1683 Sobieski arrives at Vienna and fights.
*Turks and it's allies routed.  The Ottoman Empire never recovered, ever.  They continued to hold the Balkans until WW I, with the Hapsburgs gaining much of east-central Europe.  Thanks to Sobieski, Christianity in Europe was preserved, and the Turks were prevented from installing Islam, which would have arguably set back European civilization by centuries.

Other references
Funk & Wagnalls Encyclopedia, Standard Reference Works Publishing Co. Inc. New York
Atlas of World History, Penguin Books, London 1974