>>It is interesting to note that the cloche hat we most associate with the flapper era actually made its first appearance in 1916<<
Yes, the First World War had an effect in simplifying women's fashions, due to the fact that many women became involved in the war effort, thus making more practical and less elaborate attire a necessity. I have in my possession somewhere, a catalogue from around 1916-17 which was produced by a Manchester department store, Oxendales. It is very interesting to study the fashions, certainly, women's headgear was smaller and less elaborate than before the war, with neat "bowler" type hats depicted, as well as the cloche styles. The simpler styles of the 1920's (shorter skirts, cloche hats, looser, less restrictive silhouettes), did have their roots in World War One.
Regards,
Lucy