There is a gaping void in the historiography of the Women's Auxiliary Army Corps (WAAC), later called the Queen Mary's Army Auxiliary Corps QMAAC), brought about by the absence of an informed understanding of the crucial role played by the young women seconded from British post office exchanges to serve as telephonists and telegraphists in France in 1917. Specifically attached to Royal Engineers' signal units in British Expeditionary Force army bases and all three echelons of its General Headquarters, their arrival ensured the continued smooth operation of the army's vital lines of communication. This article examines how their key role as professional technologists within a tightly secured military sector made a significant contribution to the final successful outcome of the conflict. Questions can be raised why their skills were never later addressed within the historiography, and it may be concluded that adequate recognition is long overdue.