During the Second World War, the Hospital became part of the Emergency Medical Scheme (EMS) under the control of University College Hospital (UCH). In 1941, UCH established Out-patients and Casualty Departments in one of the wards. The hospital was protected by sandbags and survived the bombings although some landed close by.
In 1944, trainee nurses from Peace Memorial Hospital joined other trainees from London Hospitals to nure the wounded from the D-Day Allied invasion of Normandy. They were sent to a Casualty Clearing Station in Chertsey for 4 months.