Cika wannan magana: Tsakanin ayyukan, Hahn ya koma Berlin, inda ya sami damar komawa tsohuwar dakin gwaje-gwajensa kuma ya taimaka wa Meitner tare da bincikenta. A watan Satumbar 1917 yana ɗaya daga cikin jami'ai uku, waɗanda aka ɓoye a cikin rigunan Austriya, waɗanda aka aika zuwa gaban Isonzo a Italiya don neman wuri mai dacewa don kai hari, ta amfani da sabbin "minewerfers" da aka haɓaka wanda a lokaci guda ya jefa ɗaruruwan kwantena na guba mai guba a kan maƙasudin abokan gaba. Sun zabi wani wuri inda Italiyanci Italiyanci ke da kariya a cikin wani kwari mai zurfi don girgijen gas zai ci gaba. Yaƙin Caporetto ya keta layin Italiyanci kuma Central Powers sun mamaye yawancin arewacin Italiya. A shekara ta 1918
Rundunar Jamus a yammacin ta rushe ta hanyar Allies 'bayan da aka saki gas daga magungunan su. A wannan lokacin rani an yi wa Hahn guba da phosgene ba da gangan ba yayin gwajin sabon abin rufe fuska. A karshen yakin ya kasance a fagen a mufti a kan wani sirri manufa don gwada wani tukunya cewa mai tsanani da kuma saki wani girgije na arsenicals.