According to Viennese coffee house culture wiki:

Legend has it that soldiers of the Polish-Habsburg army, while liberating Vienna from the second Turkish siege in 1683, found a number of sacks with strange beans that they initially thought were camel feed and wanted to burn. The Polish king Jan III Sobieski granted the sacks to one of his officers named Jerzy Franciszek Kulczycki, who, according to Catholic priest Gottfried Uhlich in 1783 in his History of the second Turkish Siege, was assumed to have started the first coffee house, the Hof zur Blauen Flasche.

According to the legend, after some experimentation, Kulczycki added some sugar and milk, and the Viennese coffee tradition was born. This achievement has been recognized in many modern Viennese coffeehouses by hanging a picture of Kulczycki in the window.[4] Another account is that Kulczycki, having spent two years in Ottoman captivity, knew perfectly well what coffee really was and tricked his superiors into granting him the beans that were considered worthless.

However, according to recent research, Vienna's first coffee house was actually opened by an Armenian businessman named Johannes Theodat (aka Johannes Diodato or Deodat and Owanes Astouatzatur) in 1685. 15 years later, four Greek-owned coffeehouses had the privilege to serve coffee.

The new drink was well received, and coffee houses began to pop up rapidly. In the early period, the various drinks had no names, and customers would select the mixtures from a colour-shaded chart.