Mohammed IV mobilized an army of 300,000 men and sent it forth under his vizier, Kara Mustapha, (Kuprili's successor) to destroy Christendom and to conquer Europe. Reaching Vienna July 7, 1683, the army quickly invested the city and cut it off from the world. Emperor Leopold had escaped the net and was several miles away. Nearby was the prince of Lorraine, with an army of 33,000 Austrians, awaiting the succor promised by John Sobieski, king of Poland, and an opportunity to relieve the besieged capital. Count Rudiger von Starhemberg, in command of the forces in Vienna, called for a volunteer to carry a message through the Turkish lines to hurry along the rescue. He found him in the person of Franz George Kolschitzky, who had lived for many years among the Turks and knew their language and customs. On August 13, 1683, Kolschitzky donned a Turkish uniform, passed through the enemy's lines and reached the Emperor's army across the Danube. Several times he made the perilous journey between the camp of the prince of Lorraine and the garrison of the governor of Vienna. One account says that he had to swim the four intervening arms of the Danube each time he performed the feat. His messages did much to keep up the morale of the city's defenders. At length King John and his army of rescuing Poles arrived and were consolidated with the Austrians on the summit of Mount Kahlenberg. It was one of the most dramatic moments in history. The fate of Christian Europe hung in the balance. Everything seemed to point to the triumph of the crescent over the cross. Once again Kolschitzky crossed the Danube, and brought back word concerning the signals that the prince of Lorraine and King John would give from Mount Kahlenberg to indicate the beginning of the attack. Count Starhemberg was to make a sortie at the same time. [Illustration: FRANZ GEORGE KOLSCHITZKY, PATRON SAINT OF VIENNA COFFEE LOVERS] The battle took place September 12, and thanks to the magnificent generalship of King John, the Turks were routed. The Poles here rendered a never-to-be-forgotten service to all Christendom. The Turkish invaders fled, leaving 25,000 tents, 10,000 oxen, 5,000 camels, 100,000 bushels of grain, a great quantity of gold, and many sacks filled with coffee--at that time unknown in Vienna. The booty was distributed; but no one wanted the coffee. They did not know what to do with it; that is, no one except Kolschitzky. He said, "If nobody wants those sacks, I will take them", and every one was heartily glad to be rid of the strange beans. But Kolschitzky knew what he was about, and he soon taught the Viennese the art of preparing coffee. Later, he established the first public booth where Turkish coffee was served in Vienna.