▁ 1 9 3 0 , ▁ ▁when ▁he ▁ ▁obtained ▁a ▁position ▁at ▁the ▁University ▁of ▁Hamburg ▁under ▁the ▁Nobel ▁Prize - win ning ▁scient ist ▁Otto ▁Stern . ▁As ▁non - A ry ans , ▁Stern ▁and ▁Fr isch ▁were ▁dismiss ed ▁after ▁Hitler ' s ▁acc ession . ▁Stern ▁found ▁Fr isch ▁a ▁position ▁in ▁Britain ▁with ▁Patrick ▁Black ett ▁at ▁Bir beck ▁College ▁at ▁the ▁University ▁of ▁London , ▁and ▁a ▁grant ▁from ▁the ▁Academ ic ▁Ass istance ▁Council . ▁He ▁followed ▁this ▁with ▁a ▁five - year ▁st int ▁at ▁the ▁N iels ▁Bo hr ▁Institute ▁in ▁C open hagen ▁with ▁N iels ▁Bo hr ▁where ▁he ▁increasing ly ▁special ised ▁in ▁nuclear ▁physics , ▁particularly ▁the ▁physics ▁of ▁neut rons , ▁which ▁had ▁been ▁discovered ▁by ▁James ▁Ch ad wick ▁in ▁ 1 9 3 2 . ▁O li ph ant ▁invited ▁Fr isch ▁to ▁come ▁to ▁the ▁University ▁of ▁B irmingham ▁in ▁the ▁summer ▁of ▁ 1 9 3 9 . ▁When ▁the ▁out break ▁of ▁the ▁Second ▁World ▁War ▁in ▁September ▁ 1 9 3 9 ▁prevent ed ▁his ▁return ▁to ▁C open hagen , ▁O li ph ant ▁found ▁him ▁a ▁position ▁at ▁the ▁University ▁of ▁B irmingham . ▁ ▁N uc lear ▁f ission ▁ ▁During ▁the ▁Christmas ▁hol iday ▁in ▁ 1 9 3 8 , ▁Fr isch ▁visited ▁his ▁a unt ▁L ise ▁Me it ner ▁in ▁K ung äl v ▁in ▁Sweden , ▁where ▁she ▁had ▁re located ▁after ▁Germany