The most popular theory about the birth of the necktie starts with
the Thirty Years War (1618-1648). Some of the best soldiers fighting
on behalf of the King of France were horsemen from Croatia. After
the war, these Croatian soldiers were presented to Louis the XIII
as war heroes, and it just so happens that these Croats were wearing
brightly colored silks around their necks. Louis, well known to
be a bit of a dandy himself, was taken by the style. Thus the "cravat"
(a derivation of "Croat") was born and soon became popular
with aristocrats throughout Europe.
These early cravats of the aristocracy were very complicated to
tie. They resembled elaborate floppy bowties more than the neckties
of today. The modern necktie was launched in late-19th century England,
and came to be known as the four-in-hand.