Attached is a black and white illustration of a commercially produced musette bag for American officers during World War I.
American Army officers, like those they commanded, had no particular interest in a musette (we have learned that a "musette" is a small French wind instrument, not unlike a bag-pipe). The bag of canvas and leather pictured herein was intended for personal effects that would be needed while on the march: stationery,toiletries, housewives).
Due to the French prowess involving all matters military during the Eighteenth and Nineteenth Centuries, the English language is lousey with French military terms, many of which are very much in use today.
