These three articles from THE STARS AND STRIPES of W.W. I reported on the U.S. Army Campaign hat which was a well-loved uniform item and most Doughboys were pretty choked-up to see that it was going to be replaced by a piece of millinery as slovenly as the overseas cap.
The Campaign Hat was first issued in 1911; these lids were worn by both the U.S. Marine Corps and the Army and many in these two groups tended to feel that the hat generated a certain prestige as well as an undeniable sense of military swank that encouraged their enlistments in the first place. There was a deep sense shared by many that the wool overseas cap was a very poor swap for the broad-brimmed campaign hat. However the lids were expensive to manufacture (produced from Argentine rabbit fur) and difficult to maintain in the French rains.