During the Prussian wars of the 17th century, Croatian mercenaries would wear colorful "scarves" around their necks to, among other things, denote rank and distinguish officer from enlisted man. The French, who were fighting alongside the Croats, were mightily impressed with this fashion innovation, and took the idea back home with them; adopting it as their own. The resulting neck adornments were called ‘cravats’, and became quite the rage among the upper crust of French society. Whether or not these cravats first spawned the bow tie, and then the straight tie, or the other way around is not known. What is most likely, is that they evolved together and concurrently. Be this as it may, the bow tie had been born.
 

HOW TO TIE A BOWTIE