So who is Cloos Crosby anyway and why does everyone think he made fifes for Civil War soldiers? First of all, Cloos and Crosby are two entirely different individuals.
Walter Crosby was a fifemaker in Boston from 1829 to 1872. It is reported in several 1930s Boston town histories that he made a fife that sold like wildfire during the Civil War. His mark, according to the surviving example at the Library of Congress was W.A. CROSBY / BOSTON. At this time we know of no one who has found such a fife.
There is a reference in Helen Ayars' book Contributions of the Music Industries of Boston 1640 to 1936 (New York: 1937), p. 212 to the "popular Crosby fifes used in the Civil War." While Ayars was generally on target with much of her information, we find it hard to believe that virtually none have survived, if they were made in such numbers. So, judgment should be reserved on her statement unless something more turns up.
George and Frederick Cloos were German woodwind instrument makers who operated a factory in Brooklyn from 1862 to 1945 when they sold the business to Penzel Muller (who operated the factory for 10 more years before shutting it down). We don't know how the connection with Crosby was made, but in any event, Cloos started making the Crosby model fife, whose distinguishing characteristic is the long tapered ferrules of German silver. Their mark was CROSBY in a sort of semi-circle over a capital G with a superimposed C enclosed by marks that look like this: < > That would be a Crosby model made by Cloos.
Although we have never been able to prove that the Cloos Crosby model was popular in the Civil War (actually, examination of patent records indicates that the machinery and methods used to make tapered metal ferrules weren't around until about 1869, which is definitely post war), we do know that the model was extremely popular with the post war civilian fife and drum corps.
The Cloos factory turned out thousands, offering several models made of various woods and metals, and competitors turned out a similar amount of cheap fakes (we know of one made of ebonite marked CROSBY and MADE IN FRANCE). We have also seen fifes marked GROSBY, although a large number of these copies were left unmarked.
Unless something more convincing comes up, we would consider the Civil War claims of Cloos fifes questionable at best, but don't let that stop you from collecting the Cloos fifes. They tend to play very sweetly in the high tones (though not quite so sweetly in the low tones), and you will own a piece of real "ancient" history.