John A. Cranston, who had also come from Glasgow to Aberdeen with Soddy as a research assistant, was drafted in March 1915.  Hitchins continued Cranston's research before she herself was drafted for war work in 1916.  This research resulted in the successful identification of a new element in the decay chain between uranium-235 and actinium, later named protactinium. The discovery of protactinium completed the early version of the periodic table proposed by Dmitri Mendeleev, who predicted the existence of an element between thorium and uranium in 1871.  The same isotope, Pa, was independently discovered around the same time by Otto Hahn and Lise Meitner.
Soddy and Cranston published their paper in 1918. Although Hitchins was not included as a co-author, Soddy gave Hitchins significant credit for the contributions she had made to the research: