On September 1, 1939, when German panzer divisions rolled into Poland, few Canadians would have guessed that the Second World War would last until May 8, 1945 in Europe and August 15 in the Japanese theatre. Even fewer would have expected the Liberal government of William Lyon Mackenzie King to embark on a program of social welfare policies that became the foundation of modern Canadian life. But, as the Canadian economy recovered from the devastation of the 1930s and full employment developed through the creation of war industries, federal civil servants began to plan for the future. Health insurance was once more on the political agenda. But was this a project that would be supported by the public? By politicians? By doctors and other health care professionals? As we will see, each group had its own reasons for supporting or opposing the development of a national health insurance system.