Introduction The International Health Conference convened in New York in 1946 recorded its appreciation to Mackenzie. He chaired the Drafting Committee and signed the final act to establish the WHO, on authority granted by the British Foreign Minister. Mackenzie arrived at this position after a range of international health work that was unmatched.
Method The paper draws on family papers, Mackenzie's publications, League of Nations' Health Organization Archives, Sprigings recent biographic essay Feed the people and prevent disease, and be damned to their politics,1 and Haswell's unpublished biography, The Man Who Stopped a War.
Results In 1922/1923, Mackenzie served in Russia with Nansen in the world's first large-scale multinational humanitarian intervention. He encountered not only famine, but cholera and epidemics of typhus and malaria of unprecedented scale. In 1928, now with the League of Nations' Health Organization, he helped to control a dengue epidemic that was paralysing economic life in Greece. Mackenzie's successes in epidemic control permitted him to nudge the Organization towards wider health engagement with several European countries, including England, Ireland and Scotland, and to dramatic assignments in Bolivia, Liberia and China.
Conclusions The scope and working methods of today's international health institutions evolved from the epidemiological work of pioneers in the League of Nations' Health Organization from Australia, Denmark, France, Germany, Italy, Poland, Switzerland, the UK, the USA and other countries. Those seeking to reform practices in humanitarian relief or in global health would benefit from studying this historical background.