Dunglass had volunteered for active military service shortly after Chamberlain left Downing Street. The consequent medical examination revealed that Dunglass had a hole in his spine surrounded by tuberculosis in the bone. Without surgery he would have been unable to walk within a matter of months. An innovative and hazardous operation was performed in September 1940, lasting six hours, in which the diseased bone in the spine was scraped away and replaced with healthy bone from the patient's shin.