Shouldn't it be the 16th century, not the 18th? The Siege of Vienna is 1529. Turks were a spent force after that.
Any Turkish army marching on Vienna on during the 18th Century wouldn't be able to even cross the straits into Greece. Especially if they are all wielding swords and riding elephants :)
Münchhausen *did* fight in the Austro-Russian–Turkish War of 1735-1739.
https://en.wikipedia.org/wiki/Austro-Russian–Turkish_War_(1735–39)
I am not certain about the elephants, but they did use swords a lot.
https://upload.wikimedia.org/wikipedia/commons/d/d5/TurkischeHauptArmeeHochenleitterBGHistory_%28randlos%29.jpg
https://upload.wikimedia.org/wikipedia/commons/9/96/Segnung_von_Kanonen_durch_den_Mufti_%28randlos%29.jpg
http://www.artvalue.com/photos/auction/0/48/48462/circle-of-vernet-emile-jean-ho-reiterschlacht-im-russisch-tur-2649523.jpg
Actually, it'd be more accurate to say it was the Battle Of Vienna 1683 that put an end to all Ottoman expansion in Europe and started its gradual decline.
Also, in the 18th Century the Turks would not have had to cross any straits to Greece because they were already there.
"facts are stupid things" Ronald Reagan