The Oxford Extra-Mural Unit of the Ministry of Home Security (OEMU) came into existence in late 1939 when the ministry's newly-created Research & Experiments Branch (later to be the Research & Experiments Department) commissioned research from the Department of Human Anatomy, Oxford University, on the physiological effects of ground shock waves and blast. The ensuing experiments were conducted by Solly Zuckerman and the findings published as a Civil Defence Research Committee paper The Effects of direct concussion on monkeys in underground shelters, RC 65, December 1939 (OEMU Report No.1).
OEMU was one of a number of groups in research institutions that carried out investigations on behalf of the ministry. It is likely that the choice of the Department of Anatomy at Oxford to carry out the necessary physiological research was influenced by Zuckerman's friend J.D. Bernal, already a member of CDRC and advising MOHS on aspects of air-raid shelter design.
The Unit was directed by Zuckerman under the general direction, until 1944, of the Professor of Anatomy at Oxford, Wilfrid le Gros Clark. At the Research & Experiments Department end direction of OEMU's research was in the hands of the Physics & Engineering Research section, RE.2, the head of which was Professor W.N. Thomas. The staff of the Unit were university personnel, with the exception of some members of the Casualty Survey field teams who were, from 1941, employees of the Research & Experiments Department.
An administrative history of the Ministry of Home Security is to be found in Cantwell, John D. The Second World War: a guide to documents in the Public Record Office, 2nd edition, HMSO, 1993 (Public Record Office Handbooks no. 15).