I was told by someone who heard from the father of R' Lichter (one of the Krasna rebbes today, a grandson of the shu"t Kavanos Halev) who himself was from Frauenkirchen that in the town's shul there hung a tri-cornered hat that origionated from the Spanish expulsion which the chazzan would don for the yomim noraim services. I'm sure you know, the sheva kehillos were established by mainly Sephardic jews.In the sefer Minhagei Amsterdam (5762, pg. 183) the author brings that at burials the mourners would don a three-cornered hat. (See also pg. 49) where the author suggest that this custom came from the goyim)
Ovadya, these are excellent sources. Thanks!Of course the Spanish hat was considerably later than the expulsion; probably 18th century.Rabbi Daniel Prosstitz, of the Pressburg beit din, is depicted wearing a tricorner hat. http://photos.geni.com/p7/7568/3547/53444836efa42983/daniel_prostitz_medium.jpgMy guess is that this is the 1820s or even later (d. 1846).
Interesting factoids from Wikipedia:"The tricorne appeared as a result of the evolution of the broad brim round hat used by Spanish soldiers in Flanders during the 17th century. By pledging (binding) the brims, a triangular shape was obtained, and since the corners offered protection from the rainy Flemish weather, this shape was favored by Spanish soldiers. In 1667, war broke out between France and Spain in the Spanish Netherlands. During the subsequent military struggle, its use spread to the French armies. The style was brought back to France, where its usage spread to the French population and the royal court of King Louis XIV, who made it fashionable throughout Europe, both as a civilian and military wear."In France, synagogue officiants (usually not rabbis), wear the tricorne on formal occasions. In the French navy and air force, tricorn are still worn by women as a piece of uniform." Old minhagim die hard!