Telephone switching once required a person at a board to complete every call. In wartime, that skill was operationally essential, and the people who held it were overwhelmingly women.
Manual switching was a trained specialty
An operator physically connected circuits with cords, holding several conversations and pending connections in mind while working at speed under continuous demand.
Speed mattered enormously in military use, where a delay in connecting a call could delay an order, and experienced operators worked several times faster than untrained personnel.
The commercial telephone industry had trained a large workforce in exactly this skill, and it was almost entirely female, so the recruiting pool was defined before anyone chose it.
Language requirements narrowed the pool further
Connecting calls across allied forces required operators fluent in more than one language, able to switch between them while working a board at full speed.
That combination of bilingual fluency and switchboard training was rare, and recruitment ran through advertisements seeking precisely those two qualifications together.
Applicants also underwent security vetting and training in military procedure, since the calls being connected carried operational information that assumed a disciplined operator on the line.
They worked near the operations they served
Operators were posted where the communications were needed rather than safely behind the lines, which meant working in damaged buildings and under conditions the job description had not described.
They wore uniforms, followed military discipline and were subject to orders, and the work continued through bombardment because the communications could not stop.
Shifts ran continuously, which meant boards were staffed overnight and through periods when the surrounding facility was being evacuated for everyone whose presence was not essential.
Status followed the pattern of other women's wartime service
Despite the uniforms and the discipline, their formal classification was disputed, which meant the benefits and recognition extended to other personnel were not straightforwardly available.
Resolution came long afterward, following campaigns by the women themselves, and by then many of those affected had died without receiving it.
The delay is instructive: the question was never whether the work had been performed under orders, but which administrative category had been written down at the time of recruitment.
Automation ended the occupation entirely
Mechanical and then electronic switching removed the need for a person in the circuit, and one of the largest categories of skilled female employment disappeared over a few decades.
The disappearance was gradual enough to attract little attention, which is generally how large occupational categories vanish, and the skill it required is now difficult to describe to anyone who never saw it performed.