Upon arrival in France, the Army recognized that the M1912 Service or Campaign Hat was cumbersome to carry and to pack and sought an alternative that was more compact and portable. Sometime in 1918 wool overseas caps were introduced as an acceptable head covering for the Doughboy in France, hence the name 'overseas cap.' These caps were not intended for use on the front lines, where the wearing of helmets was required at all times. They originally were not intended for stateside use, which further reinforces the name 'overseas cap.'
These caps could be easily folded in half and when stowed in a pocket or haversack, only occupied the space of a folded handkerchief. Overseas caps varied in quality and style and were manufactured from various types and qualities of wool. Many were manufactured by French and British tailors. The addition of collar disk insignia to the left side of the cap was most often seen. US collar disks or branch of service disks were acceptable for wearing on the overseas cap.
"The production of the overseas cap for the American Expeditionary Forces was likewise an extensive undertaking. When the requisition for overseas caps came from France, it was not possible to design one here because of a lack of knowledge as to what was required... As soon as [a] sample was received a meeting of cap makers was called in New York, and 100 manufacturers attended. One and all agreed to turn over their factories to the exclusive production of overseas caps until all requirements were met. It took these cap makers only two weeks to turn out the first order. In all 4,972,000 caps were delivered." The concluding paragraph contains more venomous comments as to what these American milliners thought of the lid. This information was gleaned from the book: America's Munitions, 1917-1918.
British Style Overseas Cap
Note that if you choose to wear a British Style cap, the British buttons must be replaced with US eagle buttons.
British Made for US Overseas Cap
Very Rare Cotton Overseas Cap
French Pattern Overseas Cap
The Style of the Following French Cap Was copied for Doughboy Use in Shades of Mustard Wool