In July 1914—shortly before the outbreak of World War I —Hahn was called to active duty with the army in a Landwehr regiment. Meitner undertook X-ray technician training, and a course on anatomy at the city hospital in Lichterfelde. Meanwhile, she completed both the work on the beta ray spectrum that she had begun before the war with Hahn and Baeyer, and her own study of the uranium decay chain. In July 1915, she returned to Vienna, where she joined the Austrian Army as an X-ray nurse-technician. Her unit was deployed to the Eastern front in Poland, and she also served on the Italian front before being discharged in September 1916.