In spite of the inconveniences, he remarked the education system as "excellent." He served as a bell boy, ringing church bell every morning at 6. Due to economic depression the family moved to Athus, a prosperous region with steel mills, in 1907. He entered German-speaking school. After two years he was asked to look after his uncle who was disabled with cerebral haemorrhage in Longlier. He dropped out of school and practically nursed his uncle for several years. At the outbreak of the First World War he was apprenticed to steel mills and worked as an industrial designer. Inspired by Winston Churchill, then British Minister of War, he joined the resistance and volunteered in British Intelligence Service in which he served during the whole war. At the end of the war he was decorated with the Interallied Medal along with veteran status. He then wanted to continue education. Since he had no formal secondary education, particularly required for medicine course, such as in Greek and Latin, he tried to join School of Mining in Liège. By that time Marcel Florkin became head of the Direction of Higher Education in Belgium's Ministry of Public Instruction, and under his administration passed the law that enabled war veterans to pursue higher education without diploma or other examinations. As an honour to his war service, he was given admission to the University of Liège in 1922 to study medicine. He obtained his degree of Doctor of Medicine in 1928. Career Claude received travel grants from Belgian government for his doctoral thesis on the transplantation of mouse cancers into rats. With this he worked his postdoctoral research in Berlin during the winter of 1928–1929, first at the Institut für Krebsforschung, and then at the Kaiser Wilhelm Institute for Biology, Dahlem, in the laboratory of tissues culture of Prof. Albert Fischer. Back in Belgium he received fellowship in 1929 from the Belgian American Educational Foundation (Commission for Relief in Belgium, CRB) for research in the United States. He applied for the Rockefeller Institute (now the Rockefeller University) in New York, USA. Simon Flexner, then Director, accepted his proposal to work on the isolation and identification of the Rous sarcoma virus. In September 1929 he joined the Rockefeller Institute. In 1930, he discovered the process of cell fractionation, which was groundbreaking in his time. The process consists of grinding up cells to break the membrane and release