In the US Navy, "yeoman" is an enlisted rating charged with performing secretarial and administrative tasks. During World War I, at a time when the Navy entirely excluded women, US Navy Secretary Josephus Daniels took advantage of a loophole in the Naval Reserve Act of 1916 to start inducting women into the Navy starting in 1917 under the rating of "Yeoman (F)", with the "F" standing for "female."
It turned out that the 1916 law did not specify male or female, calling only for the "all persons who may be capable of performing special useful service for coastal defense" as "yeomen." Secretary Daniels asserted that "yeomen" did not preclude female service and unilaterally began inducting women into the Naval Reserve.
All told, 11,274 women served as Yeomen (F) during World War I. Most were stationed in Washington DC and performed clerical work such as typing, bookkeeping, and answering telephones. A small handful became involved in more unusual jobs, such as radio operators, electricians, draftsmen, pharmacists, photographers, telegraphers, fingerprint experts, chemists, torpedo assemblers, and camouflage designers.
The Yeomen (F) were not required to attend normal naval boot camp, but in all other respects were treated exactly the same as their male yeomen counterparts, even earning the same salary ($28.75 per month). The Yeomen (F) were taught to march and marched in a variety of public rallies. The Yeoman (F) uniform was reminiscent of a traditional "sailor-style" schoolgirl uniform, with kerchiefs, long skirts, and broad brimmed hats.
The Yeomen (F) were quickly demobilized upon the end of hostilities, but were granted honorable discharges, full veterans' benefits, and access to all the normal naval veterans' associations. After 1918, women would not be granted entry to the Naval Reserve again until World War II.